Node.js module

child_process

The 'node:child_process' module enables spawning and controlling subprocesses from Node.js. It supports synchronous and asynchronous execution via exec, execFile, spawn, and fork functions.

Child processes can inherit stdio, communicate via IPC channels, and return exit codes. This module is essential for leveraging external commands, implementing parallel work, and managing worker processes.

Works in Bun

Core functionality works. The Stream class is not exported. IPC cannot send socket handles between processes; Node.js <> Bun IPC can be used with JSON serialization. Some process properties are missing.

class ChildProcess
Instances of the ChildProcess represent spawned child processes.
Instances of ChildProcess are not intended to be created directly. Rather, use the spawn, exec,execFile, or fork methods to create instances of ChildProcess.
- readonly channel?: null | Pipe
  The subprocess.channel property is a reference to the child's IPC channel. If no IPC channel exists, this property is undefined.
- readonly connected: boolean
  The subprocess.connected property indicates whether it is still possible to send and receive messages from a child process. When subprocess.connected is false, it is no longer possible to send or receive messages.
- readonly exitCode: null | number
  The subprocess.exitCode property indicates the exit code of the child process. If the child process is still running, the field will be null.
- readonly killed: boolean
  The subprocess.killed property indicates whether the child process successfully received a signal from subprocess.kill(). The killed property does not indicate that the child process has been terminated.
- readonly pid?: number
  Returns the process identifier (PID) of the child process. If the child process fails to spawn due to errors, then the value is undefined and error is emitted.
  import { spawn } from 'node:child_process'; const grep = spawn('grep', ['ssh']); console.log(`Spawned child pid: ${grep.pid}`); grep.stdin.end();
- readonly signalCode: null | Signals
  The subprocess.signalCode property indicates the signal received by the child process if any, else null.
- readonly spawnargs: string[]
  The subprocess.spawnargs property represents the full list of command-line arguments the child process was launched with.
- readonly spawnfile: string
  The subprocess.spawnfile property indicates the executable file name of the child process that is launched.
  For fork, its value will be equal to process.execPath. For spawn, its value will be the name of the executable file. For exec, its value will be the name of the shell in which the child process is launched.
- stderr: null | Readable
  A Readable Stream that represents the child process's stderr.
  If the child was spawned with stdio[2] set to anything other than 'pipe', then this will be null.
  subprocess.stderr is an alias for subprocess.stdio[2]. Both properties will refer to the same value.
  The subprocess.stderr property can be null or undefined if the child process could not be successfully spawned.
- stdin: null | Writable
  A Writable Stream that represents the child process's stdin.
  If a child process waits to read all of its input, the child will not continue until this stream has been closed via end().
  If the child was spawned with stdio[0] set to anything other than 'pipe', then this will be null.
  subprocess.stdin is an alias for subprocess.stdio[0]. Both properties will refer to the same value.
  The subprocess.stdin property can be null or undefined if the child process could not be successfully spawned.
- readonly stdio: [null | Writable, null | Readable, null | Readable, undefined | null | Writable | Readable, undefined | null | Writable | Readable]
  A sparse array of pipes to the child process, corresponding with positions in the stdio option passed to spawn that have been set to the value 'pipe'. subprocess.stdio[0], subprocess.stdio[1], and subprocess.stdio[2] are also available as subprocess.stdin, subprocess.stdout, and subprocess.stderr, respectively.
  In the following example, only the child's fd 1 (stdout) is configured as a pipe, so only the parent's subprocess.stdio[1] is a stream, all other values in the array are null.
  import assert from 'node:assert'; import fs from 'node:fs'; import child_process from 'node:child_process'; const subprocess = child_process.spawn('ls', { stdio: [ 0, // Use parent's stdin for child. 'pipe', // Pipe child's stdout to parent. fs.openSync('err.out', 'w'), // Direct child's stderr to a file. ], }); assert.strictEqual(subprocess.stdio[0], null); assert.strictEqual(subprocess.stdio[0], subprocess.stdin); assert(subprocess.stdout); assert.strictEqual(subprocess.stdio[1], subprocess.stdout); assert.strictEqual(subprocess.stdio[2], null); assert.strictEqual(subprocess.stdio[2], subprocess.stderr);
  The subprocess.stdio property can be undefined if the child process could not be successfully spawned.
- stdout: null | Readable
  A Readable Stream that represents the child process's stdout.
  If the child was spawned with stdio[1] set to anything other than 'pipe', then this will be null.
  subprocess.stdout is an alias for subprocess.stdio[1]. Both properties will refer to the same value.
  import { spawn } from 'node:child_process'; const subprocess = spawn('ls'); subprocess.stdout.on('data', (data) => { console.log(`Received chunk ${data}`); });
  The subprocess.stdout property can be null or undefined if the child process could not be successfully spawned.
- static captureRejections: boolean
  Value: boolean
  Change the default captureRejections option on all new EventEmitter objects.
- readonly static captureRejectionSymbol: typeof captureRejectionSymbol
  Value: Symbol.for('nodejs.rejection')
  See how to write a custom rejection handler.
- static defaultMaxListeners: number
  By default, a maximum of 10 listeners can be registered for any single event. This limit can be changed for individual EventEmitter instances using the emitter.setMaxListeners(n) method. To change the default for allEventEmitter instances, the events.defaultMaxListeners property can be used. If this value is not a positive number, a RangeError is thrown.
  Take caution when setting the events.defaultMaxListeners because the change affects all EventEmitter instances, including those created before the change is made. However, calling emitter.setMaxListeners(n) still has precedence over events.defaultMaxListeners.
  This is not a hard limit. The EventEmitter instance will allow more listeners to be added but will output a trace warning to stderr indicating that a "possible EventEmitter memory leak" has been detected. For any single EventEmitter, the emitter.getMaxListeners() and emitter.setMaxListeners() methods can be used to temporarily avoid this warning:
  import { EventEmitter } from 'node:events'; const emitter = new EventEmitter(); emitter.setMaxListeners(emitter.getMaxListeners() + 1); emitter.once('event', () => { // do stuff emitter.setMaxListeners(Math.max(emitter.getMaxListeners() - 1, 0)); });
  The --trace-warnings command-line flag can be used to display the stack trace for such warnings.
  The emitted warning can be inspected with process.on('warning') and will have the additional emitter, type, and count properties, referring to the event emitter instance, the event's name and the number of attached listeners, respectively. Its name property is set to 'MaxListenersExceededWarning'.
- readonly static errorMonitor: typeof errorMonitor
  This symbol shall be used to install a listener for only monitoring 'error' events. Listeners installed using this symbol are called before the regular 'error' listeners are called.
  Installing a listener using this symbol does not change the behavior once an 'error' event is emitted. Therefore, the process will still crash if no regular 'error' listener is installed.
- [events.captureRejectionSymbol]<K>(
  error: Error,
  event: string | symbol,
  ...args: AnyRest
  ): void;
- [Symbol.dispose](): void;
  Calls ChildProcess.kill with 'SIGTERM'.
- addListener(
  event: string,
  listener: (...args: any[]) => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'close',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'disconnect',
  listener: () => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'error',
  listener: (err: Error) => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'exit',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'message',
  listener: (message: Serializable, sendHandle: SendHandle) => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'spawn',
  listener: () => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
- disconnect(): void;
  Closes the IPC channel between parent and child, allowing the child to exit gracefully once there are no other connections keeping it alive. After calling this method the subprocess.connected and process.connected properties in both the parent and child (respectively) will be set to false, and it will be no longer possible to pass messages between the processes.
  The 'disconnect' event will be emitted when there are no messages in the process of being received. This will most often be triggered immediately after calling subprocess.disconnect().
  When the child process is a Node.js instance (e.g. spawned using fork), the process.disconnect() method can be invoked within the child process to close the IPC channel as well.
- emit(
  event: string | symbol,
  ...args: any[]
  ): boolean;
  Synchronously calls each of the listeners registered for the event named eventName, in the order they were registered, passing the supplied arguments to each.
  Returns true if the event had listeners, false otherwise.
  import { EventEmitter } from 'node:events'; const myEmitter = new EventEmitter(); // First listener myEmitter.on('event', function firstListener() { console.log('Helloooo! first listener'); }); // Second listener myEmitter.on('event', function secondListener(arg1, arg2) { console.log(`event with parameters ${arg1}, ${arg2} in second listener`); }); // Third listener myEmitter.on('event', function thirdListener(...args) { const parameters = args.join(', '); console.log(`event with parameters ${parameters} in third listener`); }); console.log(myEmitter.listeners('event')); myEmitter.emit('event', 1, 2, 3, 4, 5); // Prints: // [ // [Function: firstListener], // [Function: secondListener], // [Function: thirdListener] // ] // Helloooo! first listener // event with parameters 1, 2 in second listener // event with parameters 1, 2, 3, 4, 5 in third listener
  emit(
  event: 'close',
  code: null | number,
  signal: null | Signals
  ): boolean;
  emit(
  event: 'disconnect'
  ): boolean;
  emit(
  event: 'error',
  err: Error
  ): boolean;
  emit(
  event: 'exit',
  code: null | number,
  signal: null | Signals
  ): boolean;
  emit(
  event: 'message',
  message: Serializable,
  sendHandle: SendHandle
  ): boolean;
  emit(
  event: 'spawn',
  listener: () => void
  ): boolean;
- eventNames(): string | symbol[];
  Returns an array listing the events for which the emitter has registered listeners. The values in the array are strings or Symbols.
  import { EventEmitter } from 'node:events'; const myEE = new EventEmitter(); myEE.on('foo', () => {}); myEE.on('bar', () => {}); const sym = Symbol('symbol'); myEE.on(sym, () => {}); console.log(myEE.eventNames()); // Prints: [ 'foo', 'bar', Symbol(symbol) ]
- getMaxListeners(): number;
  Returns the current max listener value for the EventEmitter which is either set by emitter.setMaxListeners(n) or defaults to EventEmitter.defaultMaxListeners.
- kill(
  signal?: number | Signals
  ): boolean;
  The subprocess.kill() method sends a signal to the child process. If no argument is given, the process will be sent the 'SIGTERM' signal. See signal(7) for a list of available signals. This function returns true if kill(2) succeeds, and false otherwise.
  import { spawn } from 'node:child_process'; const grep = spawn('grep', ['ssh']); grep.on('close', (code, signal) => { console.log( `child process terminated due to receipt of signal ${signal}`); }); // Send SIGHUP to process. grep.kill('SIGHUP');
  The ChildProcess object may emit an 'error' event if the signal cannot be delivered. Sending a signal to a child process that has already exited is not an error but may have unforeseen consequences. Specifically, if the process identifier (PID) has been reassigned to another process, the signal will be delivered to that process instead which can have unexpected results.
  While the function is called kill, the signal delivered to the child process may not actually terminate the process.
  See kill(2) for reference.
  On Windows, where POSIX signals do not exist, the signal argument will be ignored, and the process will be killed forcefully and abruptly (similar to 'SIGKILL'). See Signal Events for more details.
  On Linux, child processes of child processes will not be terminated when attempting to kill their parent. This is likely to happen when running a new process in a shell or with the use of the shell option of ChildProcess:
  'use strict'; import { spawn } from 'node:child_process'; const subprocess = spawn( 'sh', [ '-c', `node -e "setInterval(() => { console.log(process.pid, 'is alive') }, 500);"`, ], { stdio: ['inherit', 'inherit', 'inherit'], }, ); setTimeout(() => { subprocess.kill(); // Does not terminate the Node.js process in the shell. }, 2000);
- listenerCount<K>(
  eventName: string | symbol,
  listener?: Function
  ): number;
  Returns the number of listeners listening for the event named eventName. If listener is provided, it will return how many times the listener is found in the list of the listeners of the event.
  @param eventName
  The name of the event being listened for
  @param listener
  The event handler function
- listeners<K>(
  eventName: string | symbol
  ): Function[];
  Returns a copy of the array of listeners for the event named eventName.
  server.on('connection', (stream) => { console.log('someone connected!'); }); console.log(util.inspect(server.listeners('connection'))); // Prints: [ [Function] ]
- off<K>(
  eventName: string | symbol,
  listener: (...args: any[]) => void
  ): this;
  Alias for emitter.removeListener().
- on(
  event: string,
  listener: (...args: any[]) => void
  ): this;
  Adds the listener function to the end of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventName and listener will result in the listener being added, and called, multiple times.
  server.on('connection', (stream) => { console.log('someone connected!'); });
  Returns a reference to the EventEmitter, so that calls can be chained.
  By default, event listeners are invoked in the order they are added. The emitter.prependListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.
  import { EventEmitter } from 'node:events'; const myEE = new EventEmitter(); myEE.on('foo', () => console.log('a')); myEE.prependListener('foo', () => console.log('b')); myEE.emit('foo'); // Prints: // b // a
  @param listener
  The callback function
  on(
  event: 'close',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  on(
  event: 'disconnect',
  listener: () => void
  ): this;
  on(
  event: 'error',
  listener: (err: Error) => void
  ): this;
  on(
  event: 'exit',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  on(
  event: 'message',
  listener: (message: Serializable, sendHandle: SendHandle) => void
  ): this;
  on(
  event: 'spawn',
  listener: () => void
  ): this;
- once(
  event: string,
  listener: (...args: any[]) => void
  ): this;
  Adds a one-time listener function for the event named eventName. The next time eventName is triggered, this listener is removed and then invoked.
  server.once('connection', (stream) => { console.log('Ah, we have our first user!'); });
  Returns a reference to the EventEmitter, so that calls can be chained.
  By default, event listeners are invoked in the order they are added. The emitter.prependOnceListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.
  import { EventEmitter } from 'node:events'; const myEE = new EventEmitter(); myEE.once('foo', () => console.log('a')); myEE.prependOnceListener('foo', () => console.log('b')); myEE.emit('foo'); // Prints: // b // a
  @param listener
  The callback function
  once(
  event: 'close',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  once(
  event: 'disconnect',
  listener: () => void
  ): this;
  once(
  event: 'error',
  listener: (err: Error) => void
  ): this;
  once(
  event: 'exit',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  once(
  event: 'message',
  listener: (message: Serializable, sendHandle: SendHandle) => void
  ): this;
  once(
  event: 'spawn',
  listener: () => void
  ): this;
- prependListener(
  event: string,
  listener: (...args: any[]) => void
  ): this;
  Adds the listener function to the beginning of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventName and listener will result in the listener being added, and called, multiple times.
  server.prependListener('connection', (stream) => { console.log('someone connected!'); });
  Returns a reference to the EventEmitter, so that calls can be chained.
  @param listener
  The callback function
  prependListener(
  event: 'close',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  prependListener(
  event: 'disconnect',
  listener: () => void
  ): this;
  prependListener(
  event: 'error',
  listener: (err: Error) => void
  ): this;
  prependListener(
  event: 'exit',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  prependListener(
  event: 'message',
  listener: (message: Serializable, sendHandle: SendHandle) => void
  ): this;
  prependListener(
  event: 'spawn',
  listener: () => void
  ): this;
- prependOnceListener(
  event: string,
  listener: (...args: any[]) => void
  ): this;
  Adds a one-timelistener function for the event named eventName to the beginning of the listeners array. The next time eventName is triggered, this listener is removed, and then invoked.
  server.prependOnceListener('connection', (stream) => { console.log('Ah, we have our first user!'); });
  Returns a reference to the EventEmitter, so that calls can be chained.
  @param listener
  The callback function
  prependOnceListener(
  event: 'close',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  prependOnceListener(
  event: 'disconnect',
  listener: () => void
  ): this;
  prependOnceListener(
  event: 'error',
  listener: (err: Error) => void
  ): this;
  prependOnceListener(
  event: 'exit',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  prependOnceListener(
  event: 'message',
  listener: (message: Serializable, sendHandle: SendHandle) => void
  ): this;
  prependOnceListener(
  event: 'spawn',
  listener: () => void
  ): this;
- rawListeners<K>(
  eventName: string | symbol
  ): Function[];
  Returns a copy of the array of listeners for the event named eventName, including any wrappers (such as those created by .once()).
  import { EventEmitter } from 'node:events'; const emitter = new EventEmitter(); emitter.once('log', () => console.log('log once')); // Returns a new Array with a function `onceWrapper` which has a property // `listener` which contains the original listener bound above const listeners = emitter.rawListeners('log'); const logFnWrapper = listeners[0]; // Logs "log once" to the console and does not unbind the `once` event logFnWrapper.listener(); // Logs "log once" to the console and removes the listener logFnWrapper(); emitter.on('log', () => console.log('log persistently')); // Will return a new Array with a single function bound by `.on()` above const newListeners = emitter.rawListeners('log'); // Logs "log persistently" twice newListeners[0](); emitter.emit('log');
- ref(): void;
  Calling subprocess.ref() after making a call to subprocess.unref() will restore the removed reference count for the child process, forcing the parent to wait for the child to exit before exiting itself.
  import { spawn } from 'node:child_process'; const subprocess = spawn(process.argv[0], ['child_program.js'], { detached: true, stdio: 'ignore', }); subprocess.unref(); subprocess.ref();
- removeAllListeners(
  eventName?: string | symbol
  ): this;
  Removes all listeners, or those of the specified eventName.
  It is bad practice to remove listeners added elsewhere in the code, particularly when the EventEmitter instance was created by some other component or module (e.g. sockets or file streams).
  Returns a reference to the EventEmitter, so that calls can be chained.
- removeListener<K>(
  eventName: string | symbol,
  listener: (...args: any[]) => void
  ): this;
  Removes the specified listener from the listener array for the event named eventName.
  const callback = (stream) => { console.log('someone connected!'); }; server.on('connection', callback); // ... server.removeListener('connection', callback);
  removeListener() will remove, at most, one instance of a listener from the listener array. If any single listener has been added multiple times to the listener array for the specified eventName, then removeListener() must be called multiple times to remove each instance.
  Once an event is emitted, all listeners attached to it at the time of emitting are called in order. This implies that any removeListener() or removeAllListeners() calls after emitting and before the last listener finishes execution will not remove them fromemit() in progress. Subsequent events behave as expected.
  import { EventEmitter } from 'node:events'; class MyEmitter extends EventEmitter {} const myEmitter = new MyEmitter(); const callbackA = () => { console.log('A'); myEmitter.removeListener('event', callbackB); }; const callbackB = () => { console.log('B'); }; myEmitter.on('event', callbackA); myEmitter.on('event', callbackB); // callbackA removes listener callbackB but it will still be called. // Internal listener array at time of emit [callbackA, callbackB] myEmitter.emit('event'); // Prints: // A // B // callbackB is now removed. // Internal listener array [callbackA] myEmitter.emit('event'); // Prints: // A
  Because listeners are managed using an internal array, calling this will change the position indices of any listener registered after the listener being removed. This will not impact the order in which listeners are called, but it means that any copies of the listener array as returned by the emitter.listeners() method will need to be recreated.
  When a single function has been added as a handler multiple times for a single event (as in the example below), removeListener() will remove the most recently added instance. In the example the once('ping') listener is removed:
  import { EventEmitter } from 'node:events'; const ee = new EventEmitter(); function pong() { console.log('pong'); } ee.on('ping', pong); ee.once('ping', pong); ee.removeListener('ping', pong); ee.emit('ping'); ee.emit('ping');
  Returns a reference to the EventEmitter, so that calls can be chained.
- send(
  message: Serializable,
  callback?: (error: null | Error) => void
  ): boolean;
  When an IPC channel has been established between the parent and child ( i.e. when using fork), the subprocess.send() method can be used to send messages to the child process. When the child process is a Node.js instance, these messages can be received via the 'message' event.
  The message goes through serialization and parsing. The resulting message might not be the same as what is originally sent.
  For example, in the parent script:
  import cp from 'node:child_process'; const n = cp.fork(`${__dirname}/sub.js`); n.on('message', (m) => { console.log('PARENT got message:', m); }); // Causes the child to print: CHILD got message: { hello: 'world' } n.send({ hello: 'world' });
  And then the child script, 'sub.js' might look like this:
  process.on('message', (m) => { console.log('CHILD got message:', m); }); // Causes the parent to print: PARENT got message: { foo: 'bar', baz: null } process.send({ foo: 'bar', baz: NaN });
  Child Node.js processes will have a process.send() method of their own that allows the child to send messages back to the parent.
  There is a special case when sending a {cmd: 'NODE_foo'} message. Messages containing a NODE_ prefix in the cmd property are reserved for use within Node.js core and will not be emitted in the child's 'message' event. Rather, such messages are emitted using the 'internalMessage' event and are consumed internally by Node.js. Applications should avoid using such messages or listening for 'internalMessage' events as it is subject to change without notice.
  The optional sendHandle argument that may be passed to subprocess.send() is for passing a TCP server or socket object to the child process. The child will receive the object as the second argument passed to the callback function registered on the 'message' event. Any data that is received and buffered in the socket will not be sent to the child. Sending IPC sockets is not supported on Windows.
  The optional callback is a function that is invoked after the message is sent but before the child may have received it. The function is called with a single argument: null on success, or an Error object on failure.
  If no callback function is provided and the message cannot be sent, an 'error' event will be emitted by the ChildProcess object. This can happen, for instance, when the child process has already exited.
  subprocess.send() will return false if the channel has closed or when the backlog of unsent messages exceeds a threshold that makes it unwise to send more. Otherwise, the method returns true. The callback function can be used to implement flow control.
  Example: sending a server object
  The sendHandle argument can be used, for instance, to pass the handle of a TCP server object to the child process as illustrated in the example below:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const subprocess = fork('subprocess.js'); // Open up the server object and send the handle. const server = createServer(); server.on('connection', (socket) => { socket.end('handled by parent'); }); server.listen(1337, () => { subprocess.send('server', server); });
  The child would then receive the server object as:
  process.on('message', (m, server) => { if (m === 'server') { server.on('connection', (socket) => { socket.end('handled by child'); }); } });
  Once the server is now shared between the parent and child, some connections can be handled by the parent and some by the child.
  While the example above uses a server created using the node:net module, node:dgram module servers use exactly the same workflow with the exceptions of listening on a 'message' event instead of 'connection' and using server.bind() instead of server.listen(). This is, however, only supported on Unix platforms.
  Example: sending a socket object
  Similarly, the sendHandler argument can be used to pass the handle of a socket to the child process. The example below spawns two children that each handle connections with "normal" or "special" priority:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const normal = fork('subprocess.js', ['normal']); const special = fork('subprocess.js', ['special']); // Open up the server and send sockets to child. Use pauseOnConnect to prevent // the sockets from being read before they are sent to the child process. const server = createServer({ pauseOnConnect: true }); server.on('connection', (socket) => { // If this is special priority... if (socket.remoteAddress === '74.125.127.100') { special.send('socket', socket); return; } // This is normal priority. normal.send('socket', socket); }); server.listen(1337);
  The subprocess.js would receive the socket handle as the second argument passed to the event callback function:
  process.on('message', (m, socket) => { if (m === 'socket') { if (socket) { // Check that the client socket exists. // It is possible for the socket to be closed between the time it is // sent and the time it is received in the child process. socket.end(`Request handled with ${process.argv[2]} priority`); } } });
  Do not use .maxConnections on a socket that has been passed to a subprocess. The parent cannot track when the socket is destroyed.
  Any 'message' handlers in the subprocess should verify that socket exists, as the connection may have been closed during the time it takes to send the connection to the child.
  send(
  message: Serializable,
  sendHandle?: SendHandle,
  callback?: (error: null | Error) => void
  ): boolean;
  When an IPC channel has been established between the parent and child ( i.e. when using fork), the subprocess.send() method can be used to send messages to the child process. When the child process is a Node.js instance, these messages can be received via the 'message' event.
  The message goes through serialization and parsing. The resulting message might not be the same as what is originally sent.
  For example, in the parent script:
  import cp from 'node:child_process'; const n = cp.fork(`${__dirname}/sub.js`); n.on('message', (m) => { console.log('PARENT got message:', m); }); // Causes the child to print: CHILD got message: { hello: 'world' } n.send({ hello: 'world' });
  And then the child script, 'sub.js' might look like this:
  process.on('message', (m) => { console.log('CHILD got message:', m); }); // Causes the parent to print: PARENT got message: { foo: 'bar', baz: null } process.send({ foo: 'bar', baz: NaN });
  Child Node.js processes will have a process.send() method of their own that allows the child to send messages back to the parent.
  There is a special case when sending a {cmd: 'NODE_foo'} message. Messages containing a NODE_ prefix in the cmd property are reserved for use within Node.js core and will not be emitted in the child's 'message' event. Rather, such messages are emitted using the 'internalMessage' event and are consumed internally by Node.js. Applications should avoid using such messages or listening for 'internalMessage' events as it is subject to change without notice.
  The optional sendHandle argument that may be passed to subprocess.send() is for passing a TCP server or socket object to the child process. The child will receive the object as the second argument passed to the callback function registered on the 'message' event. Any data that is received and buffered in the socket will not be sent to the child. Sending IPC sockets is not supported on Windows.
  The optional callback is a function that is invoked after the message is sent but before the child may have received it. The function is called with a single argument: null on success, or an Error object on failure.
  If no callback function is provided and the message cannot be sent, an 'error' event will be emitted by the ChildProcess object. This can happen, for instance, when the child process has already exited.
  subprocess.send() will return false if the channel has closed or when the backlog of unsent messages exceeds a threshold that makes it unwise to send more. Otherwise, the method returns true. The callback function can be used to implement flow control.
  Example: sending a server object
  The sendHandle argument can be used, for instance, to pass the handle of a TCP server object to the child process as illustrated in the example below:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const subprocess = fork('subprocess.js'); // Open up the server object and send the handle. const server = createServer(); server.on('connection', (socket) => { socket.end('handled by parent'); }); server.listen(1337, () => { subprocess.send('server', server); });
  The child would then receive the server object as:
  process.on('message', (m, server) => { if (m === 'server') { server.on('connection', (socket) => { socket.end('handled by child'); }); } });
  Once the server is now shared between the parent and child, some connections can be handled by the parent and some by the child.
  While the example above uses a server created using the node:net module, node:dgram module servers use exactly the same workflow with the exceptions of listening on a 'message' event instead of 'connection' and using server.bind() instead of server.listen(). This is, however, only supported on Unix platforms.
  Example: sending a socket object
  Similarly, the sendHandler argument can be used to pass the handle of a socket to the child process. The example below spawns two children that each handle connections with "normal" or "special" priority:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const normal = fork('subprocess.js', ['normal']); const special = fork('subprocess.js', ['special']); // Open up the server and send sockets to child. Use pauseOnConnect to prevent // the sockets from being read before they are sent to the child process. const server = createServer({ pauseOnConnect: true }); server.on('connection', (socket) => { // If this is special priority... if (socket.remoteAddress === '74.125.127.100') { special.send('socket', socket); return; } // This is normal priority. normal.send('socket', socket); }); server.listen(1337);
  The subprocess.js would receive the socket handle as the second argument passed to the event callback function:
  process.on('message', (m, socket) => { if (m === 'socket') { if (socket) { // Check that the client socket exists. // It is possible for the socket to be closed between the time it is // sent and the time it is received in the child process. socket.end(`Request handled with ${process.argv[2]} priority`); } } });
  Do not use .maxConnections on a socket that has been passed to a subprocess. The parent cannot track when the socket is destroyed.
  Any 'message' handlers in the subprocess should verify that socket exists, as the connection may have been closed during the time it takes to send the connection to the child.
  @param sendHandle
  undefined, or a net.Socket, net.Server, or dgram.Socket object.
  send(
  message: Serializable,
  sendHandle?: SendHandle,
  options?: MessageOptions,
  callback?: (error: null | Error) => void
  ): boolean;
  When an IPC channel has been established between the parent and child ( i.e. when using fork), the subprocess.send() method can be used to send messages to the child process. When the child process is a Node.js instance, these messages can be received via the 'message' event.
  The message goes through serialization and parsing. The resulting message might not be the same as what is originally sent.
  For example, in the parent script:
  import cp from 'node:child_process'; const n = cp.fork(`${__dirname}/sub.js`); n.on('message', (m) => { console.log('PARENT got message:', m); }); // Causes the child to print: CHILD got message: { hello: 'world' } n.send({ hello: 'world' });
  And then the child script, 'sub.js' might look like this:
  process.on('message', (m) => { console.log('CHILD got message:', m); }); // Causes the parent to print: PARENT got message: { foo: 'bar', baz: null } process.send({ foo: 'bar', baz: NaN });
  Child Node.js processes will have a process.send() method of their own that allows the child to send messages back to the parent.
  There is a special case when sending a {cmd: 'NODE_foo'} message. Messages containing a NODE_ prefix in the cmd property are reserved for use within Node.js core and will not be emitted in the child's 'message' event. Rather, such messages are emitted using the 'internalMessage' event and are consumed internally by Node.js. Applications should avoid using such messages or listening for 'internalMessage' events as it is subject to change without notice.
  The optional sendHandle argument that may be passed to subprocess.send() is for passing a TCP server or socket object to the child process. The child will receive the object as the second argument passed to the callback function registered on the 'message' event. Any data that is received and buffered in the socket will not be sent to the child. Sending IPC sockets is not supported on Windows.
  The optional callback is a function that is invoked after the message is sent but before the child may have received it. The function is called with a single argument: null on success, or an Error object on failure.
  If no callback function is provided and the message cannot be sent, an 'error' event will be emitted by the ChildProcess object. This can happen, for instance, when the child process has already exited.
  subprocess.send() will return false if the channel has closed or when the backlog of unsent messages exceeds a threshold that makes it unwise to send more. Otherwise, the method returns true. The callback function can be used to implement flow control.
  Example: sending a server object
  The sendHandle argument can be used, for instance, to pass the handle of a TCP server object to the child process as illustrated in the example below:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const subprocess = fork('subprocess.js'); // Open up the server object and send the handle. const server = createServer(); server.on('connection', (socket) => { socket.end('handled by parent'); }); server.listen(1337, () => { subprocess.send('server', server); });
  The child would then receive the server object as:
  process.on('message', (m, server) => { if (m === 'server') { server.on('connection', (socket) => { socket.end('handled by child'); }); } });
  Once the server is now shared between the parent and child, some connections can be handled by the parent and some by the child.
  While the example above uses a server created using the node:net module, node:dgram module servers use exactly the same workflow with the exceptions of listening on a 'message' event instead of 'connection' and using server.bind() instead of server.listen(). This is, however, only supported on Unix platforms.
  Example: sending a socket object
  Similarly, the sendHandler argument can be used to pass the handle of a socket to the child process. The example below spawns two children that each handle connections with "normal" or "special" priority:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const normal = fork('subprocess.js', ['normal']); const special = fork('subprocess.js', ['special']); // Open up the server and send sockets to child. Use pauseOnConnect to prevent // the sockets from being read before they are sent to the child process. const server = createServer({ pauseOnConnect: true }); server.on('connection', (socket) => { // If this is special priority... if (socket.remoteAddress === '74.125.127.100') { special.send('socket', socket); return; } // This is normal priority. normal.send('socket', socket); }); server.listen(1337);
  The subprocess.js would receive the socket handle as the second argument passed to the event callback function:
  process.on('message', (m, socket) => { if (m === 'socket') { if (socket) { // Check that the client socket exists. // It is possible for the socket to be closed between the time it is // sent and the time it is received in the child process. socket.end(`Request handled with ${process.argv[2]} priority`); } } });
  Do not use .maxConnections on a socket that has been passed to a subprocess. The parent cannot track when the socket is destroyed.
  Any 'message' handlers in the subprocess should verify that socket exists, as the connection may have been closed during the time it takes to send the connection to the child.
  @param sendHandle
  undefined, or a net.Socket, net.Server, or dgram.Socket object.
  @param options
  The options argument, if present, is an object used to parameterize the sending of certain types of handles. options supports the following properties:
- setMaxListeners(
  n: number
  ): this;
  By default EventEmitters will print a warning if more than 10 listeners are added for a particular event. This is a useful default that helps finding memory leaks. The emitter.setMaxListeners() method allows the limit to be modified for this specific EventEmitter instance. The value can be set to Infinity (or 0) to indicate an unlimited number of listeners.
  Returns a reference to the EventEmitter, so that calls can be chained.
- unref(): void;
  By default, the parent will wait for the detached child to exit. To prevent the parent from waiting for a given subprocess to exit, use the subprocess.unref() method. Doing so will cause the parent's event loop to not include the child in its reference count, allowing the parent to exit independently of the child, unless there is an established IPC channel between the child and the parent.
  import { spawn } from 'node:child_process'; const subprocess = spawn(process.argv[0], ['child_program.js'], { detached: true, stdio: 'ignore', }); subprocess.unref();
- static addAbortListener(
  signal: AbortSignal,
  resource: (event: Event) => void
  ): Disposable;
  Listens once to the abort event on the provided signal.
  Listening to the abort event on abort signals is unsafe and may lead to resource leaks since another third party with the signal can call e.stopImmediatePropagation(). Unfortunately Node.js cannot change this since it would violate the web standard. Additionally, the original API makes it easy to forget to remove listeners.
  This API allows safely using AbortSignals in Node.js APIs by solving these two issues by listening to the event such that stopImmediatePropagation does not prevent the listener from running.
  Returns a disposable so that it may be unsubscribed from more easily.
  import { addAbortListener } from 'node:events'; function example(signal) { let disposable; try { signal.addEventListener('abort', (e) => e.stopImmediatePropagation()); disposable = addAbortListener(signal, (e) => { // Do something when signal is aborted. }); } finally { disposable?.[Symbol.dispose](); } }
  @returns
  Disposable that removes the abort listener.
- static getEventListeners(
  emitter: EventEmitter<DefaultEventMap> | EventTarget,
  name: string | symbol
  ): Function[];
  Returns a copy of the array of listeners for the event named eventName.
  For EventEmitters this behaves exactly the same as calling .listeners on the emitter.
  For EventTargets this is the only way to get the event listeners for the event target. This is useful for debugging and diagnostic purposes.
  import { getEventListeners, EventEmitter } from 'node:events'; { const ee = new EventEmitter(); const listener = () => console.log('Events are fun'); ee.on('foo', listener); console.log(getEventListeners(ee, 'foo')); // [ [Function: listener] ] } { const et = new EventTarget(); const listener = () => console.log('Events are fun'); et.addEventListener('foo', listener); console.log(getEventListeners(et, 'foo')); // [ [Function: listener] ] }
- static getMaxListeners(
  emitter: EventEmitter<DefaultEventMap> | EventTarget
  ): number;
  Returns the currently set max amount of listeners.
  For EventEmitters this behaves exactly the same as calling .getMaxListeners on the emitter.
  For EventTargets this is the only way to get the max event listeners for the event target. If the number of event handlers on a single EventTarget exceeds the max set, the EventTarget will print a warning.
  import { getMaxListeners, setMaxListeners, EventEmitter } from 'node:events'; { const ee = new EventEmitter(); console.log(getMaxListeners(ee)); // 10 setMaxListeners(11, ee); console.log(getMaxListeners(ee)); // 11 } { const et = new EventTarget(); console.log(getMaxListeners(et)); // 10 setMaxListeners(11, et); console.log(getMaxListeners(et)); // 11 }
- static on(
  emitter: EventEmitter,
  eventName: string | symbol,
  options?: StaticEventEmitterIteratorOptions
  ): AsyncIterator<any[]>;
  import { on, EventEmitter } from 'node:events'; import process from 'node:process'; const ee = new EventEmitter(); // Emit later on process.nextTick(() => { ee.emit('foo', 'bar'); ee.emit('foo', 42); }); for await (const event of on(ee, 'foo')) { // The execution of this inner block is synchronous and it // processes one event at a time (even with await). Do not use // if concurrent execution is required. console.log(event); // prints ['bar'] [42] } // Unreachable here
  Returns an AsyncIterator that iterates eventName events. It will throw if the EventEmitter emits 'error'. It removes all listeners when exiting the loop. The value returned by each iteration is an array composed of the emitted event arguments.
  An AbortSignal can be used to cancel waiting on events:
  import { on, EventEmitter } from 'node:events'; import process from 'node:process'; const ac = new AbortController(); (async () => { const ee = new EventEmitter(); // Emit later on process.nextTick(() => { ee.emit('foo', 'bar'); ee.emit('foo', 42); }); for await (const event of on(ee, 'foo', { signal: ac.signal })) { // The execution of this inner block is synchronous and it // processes one event at a time (even with await). Do not use // if concurrent execution is required. console.log(event); // prints ['bar'] [42] } // Unreachable here })(); process.nextTick(() => ac.abort());
  Use the close option to specify an array of event names that will end the iteration:
  import { on, EventEmitter } from 'node:events'; import process from 'node:process'; const ee = new EventEmitter(); // Emit later on process.nextTick(() => { ee.emit('foo', 'bar'); ee.emit('foo', 42); ee.emit('close'); }); for await (const event of on(ee, 'foo', { close: ['close'] })) { console.log(event); // prints ['bar'] [42] } // the loop will exit after 'close' is emitted console.log('done'); // prints 'done'
  @returns
  An AsyncIterator that iterates eventName events emitted by the emitter
  static on(
  emitter: EventTarget,
  eventName: string,
  options?: StaticEventEmitterIteratorOptions
  ): AsyncIterator<any[]>;
  import { on, EventEmitter } from 'node:events'; import process from 'node:process'; const ee = new EventEmitter(); // Emit later on process.nextTick(() => { ee.emit('foo', 'bar'); ee.emit('foo', 42); }); for await (const event of on(ee, 'foo')) { // The execution of this inner block is synchronous and it // processes one event at a time (even with await). Do not use // if concurrent execution is required. console.log(event); // prints ['bar'] [42] } // Unreachable here
  Returns an AsyncIterator that iterates eventName events. It will throw if the EventEmitter emits 'error'. It removes all listeners when exiting the loop. The value returned by each iteration is an array composed of the emitted event arguments.
  An AbortSignal can be used to cancel waiting on events:
  import { on, EventEmitter } from 'node:events'; import process from 'node:process'; const ac = new AbortController(); (async () => { const ee = new EventEmitter(); // Emit later on process.nextTick(() => { ee.emit('foo', 'bar'); ee.emit('foo', 42); }); for await (const event of on(ee, 'foo', { signal: ac.signal })) { // The execution of this inner block is synchronous and it // processes one event at a time (even with await). Do not use // if concurrent execution is required. console.log(event); // prints ['bar'] [42] } // Unreachable here })(); process.nextTick(() => ac.abort());
  Use the close option to specify an array of event names that will end the iteration:
  import { on, EventEmitter } from 'node:events'; import process from 'node:process'; const ee = new EventEmitter(); // Emit later on process.nextTick(() => { ee.emit('foo', 'bar'); ee.emit('foo', 42); ee.emit('close'); }); for await (const event of on(ee, 'foo', { close: ['close'] })) { console.log(event); // prints ['bar'] [42] } // the loop will exit after 'close' is emitted console.log('done'); // prints 'done'
  @returns
  An AsyncIterator that iterates eventName events emitted by the emitter
- static once(
  emitter: EventEmitter,
  eventName: string | symbol,
  options?: StaticEventEmitterOptions
  ): Promise<any[]>;
  Creates a Promise that is fulfilled when the EventEmitter emits the given event or that is rejected if the EventEmitter emits 'error' while waiting. The Promise will resolve with an array of all the arguments emitted to the given event.
  This method is intentionally generic and works with the web platform EventTarget interface, which has no special'error' event semantics and does not listen to the 'error' event.
  import { once, EventEmitter } from 'node:events'; import process from 'node:process'; const ee = new EventEmitter(); process.nextTick(() => { ee.emit('myevent', 42); }); const [value] = await once(ee, 'myevent'); console.log(value); const err = new Error('kaboom'); process.nextTick(() => { ee.emit('error', err); }); try { await once(ee, 'myevent'); } catch (err) { console.error('error happened', err); }
  The special handling of the 'error' event is only used when events.once() is used to wait for another event. If events.once() is used to wait for the 'error' event itself, then it is treated as any other kind of event without special handling:
  import { EventEmitter, once } from 'node:events'; const ee = new EventEmitter(); once(ee, 'error') .then(([err]) => console.log('ok', err.message)) .catch((err) => console.error('error', err.message)); ee.emit('error', new Error('boom')); // Prints: ok boom
  An AbortSignal can be used to cancel waiting for the event:
  import { EventEmitter, once } from 'node:events'; const ee = new EventEmitter(); const ac = new AbortController(); async function foo(emitter, event, signal) { try { await once(emitter, event, { signal }); console.log('event emitted!'); } catch (error) { if (error.name === 'AbortError') { console.error('Waiting for the event was canceled!'); } else { console.error('There was an error', error.message); } } } foo(ee, 'foo', ac.signal); ac.abort(); // Abort waiting for the event ee.emit('foo'); // Prints: Waiting for the event was canceled!
  static once(
  emitter: EventTarget,
  eventName: string,
  options?: StaticEventEmitterOptions
  ): Promise<any[]>;
  Creates a Promise that is fulfilled when the EventEmitter emits the given event or that is rejected if the EventEmitter emits 'error' while waiting. The Promise will resolve with an array of all the arguments emitted to the given event.
  This method is intentionally generic and works with the web platform EventTarget interface, which has no special'error' event semantics and does not listen to the 'error' event.
  import { once, EventEmitter } from 'node:events'; import process from 'node:process'; const ee = new EventEmitter(); process.nextTick(() => { ee.emit('myevent', 42); }); const [value] = await once(ee, 'myevent'); console.log(value); const err = new Error('kaboom'); process.nextTick(() => { ee.emit('error', err); }); try { await once(ee, 'myevent'); } catch (err) { console.error('error happened', err); }
  The special handling of the 'error' event is only used when events.once() is used to wait for another event. If events.once() is used to wait for the 'error' event itself, then it is treated as any other kind of event without special handling:
  import { EventEmitter, once } from 'node:events'; const ee = new EventEmitter(); once(ee, 'error') .then(([err]) => console.log('ok', err.message)) .catch((err) => console.error('error', err.message)); ee.emit('error', new Error('boom')); // Prints: ok boom
  An AbortSignal can be used to cancel waiting for the event:
  import { EventEmitter, once } from 'node:events'; const ee = new EventEmitter(); const ac = new AbortController(); async function foo(emitter, event, signal) { try { await once(emitter, event, { signal }); console.log('event emitted!'); } catch (error) { if (error.name === 'AbortError') { console.error('Waiting for the event was canceled!'); } else { console.error('There was an error', error.message); } } } foo(ee, 'foo', ac.signal); ac.abort(); // Abort waiting for the event ee.emit('foo'); // Prints: Waiting for the event was canceled!
- static setMaxListeners(
  n?: number,
  ...eventTargets: EventEmitter<DefaultEventMap> | EventTarget[]
  ): void;
  import { setMaxListeners, EventEmitter } from 'node:events'; const target = new EventTarget(); const emitter = new EventEmitter(); setMaxListeners(5, target, emitter);
  @param n
  A non-negative number. The maximum number of listeners per EventTarget event.
  @param eventTargets
  Zero or more {EventTarget} or {EventEmitter} instances. If none are specified, n is set as the default max for all newly created {EventTarget} and {EventEmitter} objects.
function exec(
command: string,
callback?: (error: null | ExecException, stdout: string, stderr: string) => void
): ChildProcess;
Spawns a shell then executes the command within that shell, buffering any generated output. The command string passed to the exec function is processed directly by the shell and special characters (vary based on shell) need to be dealt with accordingly:
import { exec } from 'node:child_process'; exec('"/path/to/test file/test.sh" arg1 arg2'); // Double quotes are used so that the space in the path is not interpreted as // a delimiter of multiple arguments. exec('echo "The \\$HOME variable is $HOME"'); // The $HOME variable is escaped in the first instance, but not in the second.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If a callback function is provided, it is called with the arguments (error, stdout, stderr). On success, error will be null. On error, error will be an instance of Error. The error.code property will be the exit code of the process. By convention, any exit code other than 0 indicates an error. error.signal will be the signal that terminated the process.
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
import { exec } from 'node:child_process'; exec('cat *.js missing_file | wc -l', (error, stdout, stderr) => { if (error) { console.error(`exec error: ${error}`); return; } console.log(`stdout: ${stdout}`); console.error(`stderr: ${stderr}`); });
If timeout is greater than 0, the parent will send the signal identified by the killSignal property (the default is 'SIGTERM') if the child runs longer than timeout milliseconds.
Unlike the exec(3) POSIX system call, child_process.exec() does not replace the existing process and uses a shell to execute the command.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const exec = util.promisify(child_process.exec); async function lsExample() { const { stdout, stderr } = await exec('ls'); console.log('stdout:', stdout); console.error('stderr:', stderr); } lsExample();
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { exec } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = exec('grep ssh', { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param command
The command to run, with space-separated arguments.
@param callback
called with the output when process terminates.
function exec(
command: string,
options: { encoding: null | 'buffer' } & ExecOptions,
callback?: (error: null | ExecException, stdout: Buffer, stderr: Buffer) => void
): ChildProcess;
Spawns a shell then executes the command within that shell, buffering any generated output. The command string passed to the exec function is processed directly by the shell and special characters (vary based on shell) need to be dealt with accordingly:
import { exec } from 'node:child_process'; exec('"/path/to/test file/test.sh" arg1 arg2'); // Double quotes are used so that the space in the path is not interpreted as // a delimiter of multiple arguments. exec('echo "The \\$HOME variable is $HOME"'); // The $HOME variable is escaped in the first instance, but not in the second.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If a callback function is provided, it is called with the arguments (error, stdout, stderr). On success, error will be null. On error, error will be an instance of Error. The error.code property will be the exit code of the process. By convention, any exit code other than 0 indicates an error. error.signal will be the signal that terminated the process.
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
import { exec } from 'node:child_process'; exec('cat *.js missing_file | wc -l', (error, stdout, stderr) => { if (error) { console.error(`exec error: ${error}`); return; } console.log(`stdout: ${stdout}`); console.error(`stderr: ${stderr}`); });
If timeout is greater than 0, the parent will send the signal identified by the killSignal property (the default is 'SIGTERM') if the child runs longer than timeout milliseconds.
Unlike the exec(3) POSIX system call, child_process.exec() does not replace the existing process and uses a shell to execute the command.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const exec = util.promisify(child_process.exec); async function lsExample() { const { stdout, stderr } = await exec('ls'); console.log('stdout:', stdout); console.error('stderr:', stderr); } lsExample();
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { exec } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = exec('grep ssh', { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param command
The command to run, with space-separated arguments.
@param callback
called with the output when process terminates.
function exec(
command: string,
options: { encoding: BufferEncoding } & ExecOptions,
callback?: (error: null | ExecException, stdout: string, stderr: string) => void
): ChildProcess;
Spawns a shell then executes the command within that shell, buffering any generated output. The command string passed to the exec function is processed directly by the shell and special characters (vary based on shell) need to be dealt with accordingly:
import { exec } from 'node:child_process'; exec('"/path/to/test file/test.sh" arg1 arg2'); // Double quotes are used so that the space in the path is not interpreted as // a delimiter of multiple arguments. exec('echo "The \\$HOME variable is $HOME"'); // The $HOME variable is escaped in the first instance, but not in the second.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If a callback function is provided, it is called with the arguments (error, stdout, stderr). On success, error will be null. On error, error will be an instance of Error. The error.code property will be the exit code of the process. By convention, any exit code other than 0 indicates an error. error.signal will be the signal that terminated the process.
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
import { exec } from 'node:child_process'; exec('cat *.js missing_file | wc -l', (error, stdout, stderr) => { if (error) { console.error(`exec error: ${error}`); return; } console.log(`stdout: ${stdout}`); console.error(`stderr: ${stderr}`); });
If timeout is greater than 0, the parent will send the signal identified by the killSignal property (the default is 'SIGTERM') if the child runs longer than timeout milliseconds.
Unlike the exec(3) POSIX system call, child_process.exec() does not replace the existing process and uses a shell to execute the command.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const exec = util.promisify(child_process.exec); async function lsExample() { const { stdout, stderr } = await exec('ls'); console.log('stdout:', stdout); console.error('stderr:', stderr); } lsExample();
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { exec } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = exec('grep ssh', { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param command
The command to run, with space-separated arguments.
@param callback
called with the output when process terminates.
function exec(
command: string,
options: { encoding: BufferEncoding } & ExecOptions,
callback?: (error: null | ExecException, stdout: string | Buffer<ArrayBufferLike>, stderr: string | Buffer<ArrayBufferLike>) => void
): ChildProcess;
Spawns a shell then executes the command within that shell, buffering any generated output. The command string passed to the exec function is processed directly by the shell and special characters (vary based on shell) need to be dealt with accordingly:
import { exec } from 'node:child_process'; exec('"/path/to/test file/test.sh" arg1 arg2'); // Double quotes are used so that the space in the path is not interpreted as // a delimiter of multiple arguments. exec('echo "The \\$HOME variable is $HOME"'); // The $HOME variable is escaped in the first instance, but not in the second.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If a callback function is provided, it is called with the arguments (error, stdout, stderr). On success, error will be null. On error, error will be an instance of Error. The error.code property will be the exit code of the process. By convention, any exit code other than 0 indicates an error. error.signal will be the signal that terminated the process.
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
import { exec } from 'node:child_process'; exec('cat *.js missing_file | wc -l', (error, stdout, stderr) => { if (error) { console.error(`exec error: ${error}`); return; } console.log(`stdout: ${stdout}`); console.error(`stderr: ${stderr}`); });
If timeout is greater than 0, the parent will send the signal identified by the killSignal property (the default is 'SIGTERM') if the child runs longer than timeout milliseconds.
Unlike the exec(3) POSIX system call, child_process.exec() does not replace the existing process and uses a shell to execute the command.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const exec = util.promisify(child_process.exec); async function lsExample() { const { stdout, stderr } = await exec('ls'); console.log('stdout:', stdout); console.error('stderr:', stderr); } lsExample();
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { exec } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = exec('grep ssh', { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param command
The command to run, with space-separated arguments.
@param callback
called with the output when process terminates.
function exec(
command: string,
options: ExecOptions,
callback?: (error: null | ExecException, stdout: string, stderr: string) => void
): ChildProcess;
Spawns a shell then executes the command within that shell, buffering any generated output. The command string passed to the exec function is processed directly by the shell and special characters (vary based on shell) need to be dealt with accordingly:
import { exec } from 'node:child_process'; exec('"/path/to/test file/test.sh" arg1 arg2'); // Double quotes are used so that the space in the path is not interpreted as // a delimiter of multiple arguments. exec('echo "The \\$HOME variable is $HOME"'); // The $HOME variable is escaped in the first instance, but not in the second.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If a callback function is provided, it is called with the arguments (error, stdout, stderr). On success, error will be null. On error, error will be an instance of Error. The error.code property will be the exit code of the process. By convention, any exit code other than 0 indicates an error. error.signal will be the signal that terminated the process.
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
import { exec } from 'node:child_process'; exec('cat *.js missing_file | wc -l', (error, stdout, stderr) => { if (error) { console.error(`exec error: ${error}`); return; } console.log(`stdout: ${stdout}`); console.error(`stderr: ${stderr}`); });
If timeout is greater than 0, the parent will send the signal identified by the killSignal property (the default is 'SIGTERM') if the child runs longer than timeout milliseconds.
Unlike the exec(3) POSIX system call, child_process.exec() does not replace the existing process and uses a shell to execute the command.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const exec = util.promisify(child_process.exec); async function lsExample() { const { stdout, stderr } = await exec('ls'); console.log('stdout:', stdout); console.error('stderr:', stderr); } lsExample();
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { exec } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = exec('grep ssh', { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param command
The command to run, with space-separated arguments.
@param callback
called with the output when process terminates.
function exec(
command: string,
options: undefined | null | ObjectEncodingOptions & ExecOptions,
callback?: (error: null | ExecException, stdout: string | Buffer<ArrayBufferLike>, stderr: string | Buffer<ArrayBufferLike>) => void
): ChildProcess;
Spawns a shell then executes the command within that shell, buffering any generated output. The command string passed to the exec function is processed directly by the shell and special characters (vary based on shell) need to be dealt with accordingly:
import { exec } from 'node:child_process'; exec('"/path/to/test file/test.sh" arg1 arg2'); // Double quotes are used so that the space in the path is not interpreted as // a delimiter of multiple arguments. exec('echo "The \\$HOME variable is $HOME"'); // The $HOME variable is escaped in the first instance, but not in the second.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If a callback function is provided, it is called with the arguments (error, stdout, stderr). On success, error will be null. On error, error will be an instance of Error. The error.code property will be the exit code of the process. By convention, any exit code other than 0 indicates an error. error.signal will be the signal that terminated the process.
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
import { exec } from 'node:child_process'; exec('cat *.js missing_file | wc -l', (error, stdout, stderr) => { if (error) { console.error(`exec error: ${error}`); return; } console.log(`stdout: ${stdout}`); console.error(`stderr: ${stderr}`); });
If timeout is greater than 0, the parent will send the signal identified by the killSignal property (the default is 'SIGTERM') if the child runs longer than timeout milliseconds.
Unlike the exec(3) POSIX system call, child_process.exec() does not replace the existing process and uses a shell to execute the command.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const exec = util.promisify(child_process.exec); async function lsExample() { const { stdout, stderr } = await exec('ls'); console.log('stdout:', stdout); console.error('stderr:', stderr); } lsExample();
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { exec } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = exec('grep ssh', { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param command
The command to run, with space-separated arguments.
@param callback
called with the output when process terminates.
function execFile(
file: string
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
function execFile(
file: string,
options: undefined | null | ObjectEncodingOptions & ExecFileOptions
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
function execFile(
file: string,
args?: null | readonly string[]
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
function execFile(
file: string,
args: undefined | null | readonly string[],
options: undefined | null | ObjectEncodingOptions & ExecFileOptions
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
function execFile(
file: string,
callback: (error: null | ExecFileException, stdout: string, stderr: string) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
args: undefined | null | readonly string[],
callback: (error: null | ExecFileException, stdout: string, stderr: string) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
options: ExecFileOptionsWithBufferEncoding,
callback: (error: null | ExecFileException, stdout: Buffer, stderr: Buffer) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
args: undefined | null | readonly string[],
options: ExecFileOptionsWithBufferEncoding,
callback: (error: null | ExecFileException, stdout: Buffer, stderr: Buffer) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
options: ExecFileOptionsWithStringEncoding,
callback: (error: null | ExecFileException, stdout: string, stderr: string) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
args: undefined | null | readonly string[],
options: ExecFileOptionsWithStringEncoding,
callback: (error: null | ExecFileException, stdout: string, stderr: string) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
options: ExecFileOptionsWithOtherEncoding,
callback: (error: null | ExecFileException, stdout: string | Buffer<ArrayBufferLike>, stderr: string | Buffer<ArrayBufferLike>) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
args: undefined | null | readonly string[],
options: ExecFileOptionsWithOtherEncoding,
callback: (error: null | ExecFileException, stdout: string | Buffer<ArrayBufferLike>, stderr: string | Buffer<ArrayBufferLike>) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
options: ExecFileOptions,
callback: (error: null | ExecFileException, stdout: string, stderr: string) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
args: undefined | null | readonly string[],
options: ExecFileOptions,
callback: (error: null | ExecFileException, stdout: string, stderr: string) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
options: undefined | null | ObjectEncodingOptions & ExecFileOptions,
callback: undefined | null | (error: null | ExecFileException, stdout: string | Buffer<ArrayBufferLike>, stderr: string | Buffer<ArrayBufferLike>) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
args: undefined | null | readonly string[],
options: undefined | null | ObjectEncodingOptions & ExecFileOptions,
callback: undefined | null | (error: null | ExecFileException, stdout: string | Buffer<ArrayBufferLike>, stderr: string | Buffer<ArrayBufferLike>) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@param callback
Called with the output when process terminates.
function execFileSync(
file: string
): Buffer;
The child_process.execFileSync() method is generally identical to execFile with the exception that the method will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited.
If the child process intercepts and handles the SIGTERM signal and does not exit, the parent process will still wait until the child process has exited.
If the process times out or has a non-zero exit code, this method will throw an Error that will include the full result of the underlying spawnSync.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param file
The name or path of the executable file to run.
@returns
The stdout from the command.
function execFileSync(
file: string,
options: ExecFileSyncOptionsWithStringEncoding
): string;
The child_process.execFileSync() method is generally identical to execFile with the exception that the method will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited.
If the child process intercepts and handles the SIGTERM signal and does not exit, the parent process will still wait until the child process has exited.
If the process times out or has a non-zero exit code, this method will throw an Error that will include the full result of the underlying spawnSync.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param file
The name or path of the executable file to run.
@returns
The stdout from the command.
function execFileSync(
file: string,
options: ExecFileSyncOptionsWithBufferEncoding
): Buffer;
The child_process.execFileSync() method is generally identical to execFile with the exception that the method will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited.
If the child process intercepts and handles the SIGTERM signal and does not exit, the parent process will still wait until the child process has exited.
If the process times out or has a non-zero exit code, this method will throw an Error that will include the full result of the underlying spawnSync.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param file
The name or path of the executable file to run.
@returns
The stdout from the command.
function execFileSync(
file: string,
options?: ExecFileSyncOptions
): string | Buffer<ArrayBufferLike>;
The child_process.execFileSync() method is generally identical to execFile with the exception that the method will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited.
If the child process intercepts and handles the SIGTERM signal and does not exit, the parent process will still wait until the child process has exited.
If the process times out or has a non-zero exit code, this method will throw an Error that will include the full result of the underlying spawnSync.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param file
The name or path of the executable file to run.
@returns
The stdout from the command.
function execFileSync(
file: string,
args: readonly string[]
): Buffer;
The child_process.execFileSync() method is generally identical to execFile with the exception that the method will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited.
If the child process intercepts and handles the SIGTERM signal and does not exit, the parent process will still wait until the child process has exited.
If the process times out or has a non-zero exit code, this method will throw an Error that will include the full result of the underlying spawnSync.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@returns
The stdout from the command.
function execFileSync(
file: string,
args: readonly string[],
options: ExecFileSyncOptionsWithStringEncoding
): string;
The child_process.execFileSync() method is generally identical to execFile with the exception that the method will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited.
If the child process intercepts and handles the SIGTERM signal and does not exit, the parent process will still wait until the child process has exited.
If the process times out or has a non-zero exit code, this method will throw an Error that will include the full result of the underlying spawnSync.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@returns
The stdout from the command.
function execFileSync(
file: string,
args: readonly string[],
options: ExecFileSyncOptionsWithBufferEncoding
): Buffer;
The child_process.execFileSync() method is generally identical to execFile with the exception that the method will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited.
If the child process intercepts and handles the SIGTERM signal and does not exit, the parent process will still wait until the child process has exited.
If the process times out or has a non-zero exit code, this method will throw an Error that will include the full result of the underlying spawnSync.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@returns
The stdout from the command.
function execFileSync(
file: string,
args?: readonly string[],
options?: ExecFileSyncOptions
): string | Buffer<ArrayBufferLike>;
The child_process.execFileSync() method is generally identical to execFile with the exception that the method will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited.
If the child process intercepts and handles the SIGTERM signal and does not exit, the parent process will still wait until the child process has exited.
If the process times out or has a non-zero exit code, this method will throw an Error that will include the full result of the underlying spawnSync.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@returns
The stdout from the command.
function execSync(
command: string
): Buffer;
The child_process.execSync() method is generally identical to exec with the exception that the method will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited. If the child process intercepts and handles the SIGTERM signal and doesn't exit, the parent process will wait until the child process has exited.
If the process times out or has a non-zero exit code, this method will throw. The Error object will contain the entire result from spawnSync.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param command
The command to run.
@returns
The stdout from the command.
function execSync(
command: string,
options: ExecSyncOptionsWithStringEncoding
): string;
The child_process.execSync() method is generally identical to exec with the exception that the method will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited. If the child process intercepts and handles the SIGTERM signal and doesn't exit, the parent process will wait until the child process has exited.
If the process times out or has a non-zero exit code, this method will throw. The Error object will contain the entire result from spawnSync.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param command
The command to run.
@returns
The stdout from the command.
function execSync(
command: string,
options: ExecSyncOptionsWithBufferEncoding
): Buffer;
The child_process.execSync() method is generally identical to exec with the exception that the method will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited. If the child process intercepts and handles the SIGTERM signal and doesn't exit, the parent process will wait until the child process has exited.
If the process times out or has a non-zero exit code, this method will throw. The Error object will contain the entire result from spawnSync.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param command
The command to run.
@returns
The stdout from the command.
function execSync(
command: string,
options?: ExecSyncOptions
): string | Buffer<ArrayBufferLike>;
The child_process.execSync() method is generally identical to exec with the exception that the method will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited. If the child process intercepts and handles the SIGTERM signal and doesn't exit, the parent process will wait until the child process has exited.
If the process times out or has a non-zero exit code, this method will throw. The Error object will contain the entire result from spawnSync.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param command
The command to run.
@returns
The stdout from the command.
function fork(
modulePath: string | URL,
options?: ForkOptions
): ChildProcess;
The child_process.fork() method is a special case of spawn used specifically to spawn new Node.js processes. Like spawn, a ChildProcess object is returned. The returned ChildProcess will have an additional communication channel built-in that allows messages to be passed back and forth between the parent and child. See subprocess.send() for details.
Keep in mind that spawned Node.js child processes are independent of the parent with exception of the IPC communication channel that is established between the two. Each process has its own memory, with their own V8 instances. Because of the additional resource allocations required, spawning a large number of child Node.js processes is not recommended.
By default, child_process.fork() will spawn new Node.js instances using the process.execPath of the parent process. The execPath property in the options object allows for an alternative execution path to be used.
Node.js processes launched with a custom execPath will communicate with the parent process using the file descriptor (fd) identified using the environment variable NODE_CHANNEL_FD on the child process.
Unlike the fork(2) POSIX system call, child_process.fork() does not clone the current process.
The shell option available in spawn is not supported by child_process.fork() and will be ignored if set.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
if (process.argv[2] === 'child') { setTimeout(() => { console.log(`Hello from ${process.argv[2]}!`); }, 1_000); } else { import { fork } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = fork(__filename, ['child'], { signal }); child.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process }
@param modulePath
The module to run in the child.
function fork(
modulePath: string | URL,
args?: readonly string[],
options?: ForkOptions
): ChildProcess;
The child_process.fork() method is a special case of spawn used specifically to spawn new Node.js processes. Like spawn, a ChildProcess object is returned. The returned ChildProcess will have an additional communication channel built-in that allows messages to be passed back and forth between the parent and child. See subprocess.send() for details.
Keep in mind that spawned Node.js child processes are independent of the parent with exception of the IPC communication channel that is established between the two. Each process has its own memory, with their own V8 instances. Because of the additional resource allocations required, spawning a large number of child Node.js processes is not recommended.
By default, child_process.fork() will spawn new Node.js instances using the process.execPath of the parent process. The execPath property in the options object allows for an alternative execution path to be used.
Node.js processes launched with a custom execPath will communicate with the parent process using the file descriptor (fd) identified using the environment variable NODE_CHANNEL_FD on the child process.
Unlike the fork(2) POSIX system call, child_process.fork() does not clone the current process.
The shell option available in spawn is not supported by child_process.fork() and will be ignored if set.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
if (process.argv[2] === 'child') { setTimeout(() => { console.log(`Hello from ${process.argv[2]}!`); }, 1_000); } else { import { fork } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = fork(__filename, ['child'], { signal }); child.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process }
@param modulePath
The module to run in the child.
@param args
List of string arguments.
function spawn(
command: string,
options?: SpawnOptionsWithoutStdio
): ChildProcessWithoutNullStreams;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
function spawn(
command: string,
options: SpawnOptionsWithStdioTuple<StdioPipe, StdioPipe, StdioPipe>
): ChildProcessByStdio<Writable, Readable, Readable>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
function spawn(
command: string,
options: SpawnOptionsWithStdioTuple<StdioPipe, StdioPipe, StdioNull>
): ChildProcessByStdio<Writable, Readable, null>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
function spawn(
command: string,
options: SpawnOptionsWithStdioTuple<StdioPipe, StdioNull, StdioPipe>
): ChildProcessByStdio<Writable, null, Readable>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
function spawn(
command: string,
options: SpawnOptionsWithStdioTuple<StdioNull, StdioPipe, StdioPipe>
): ChildProcessByStdio<null, Readable, Readable>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
function spawn(
command: string,
options: SpawnOptionsWithStdioTuple<StdioPipe, StdioNull, StdioNull>
): ChildProcessByStdio<Writable, null, null>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
function spawn(
command: string,
options: SpawnOptionsWithStdioTuple<StdioNull, StdioPipe, StdioNull>
): ChildProcessByStdio<null, Readable, null>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
function spawn(
command: string,
options: SpawnOptionsWithStdioTuple<StdioNull, StdioNull, StdioPipe>
): ChildProcessByStdio<null, null, Readable>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
function spawn(
command: string,
options: SpawnOptionsWithStdioTuple<StdioNull, StdioNull, StdioNull>
): ChildProcessByStdio<null, null, null>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
function spawn(
command: string,
options: SpawnOptions
): ChildProcess;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
function spawn(
command: string,
args?: readonly string[],
options?: SpawnOptionsWithoutStdio
): ChildProcessWithoutNullStreams;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
@param args
List of string arguments.
function spawn(
command: string,
args: readonly string[],
options: SpawnOptionsWithStdioTuple<StdioPipe, StdioPipe, StdioPipe>
): ChildProcessByStdio<Writable, Readable, Readable>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
@param args
List of string arguments.
function spawn(
command: string,
args: readonly string[],
options: SpawnOptionsWithStdioTuple<StdioPipe, StdioPipe, StdioNull>
): ChildProcessByStdio<Writable, Readable, null>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
@param args
List of string arguments.
function spawn(
command: string,
args: readonly string[],
options: SpawnOptionsWithStdioTuple<StdioPipe, StdioNull, StdioPipe>
): ChildProcessByStdio<Writable, null, Readable>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
@param args
List of string arguments.
function spawn(
command: string,
args: readonly string[],
options: SpawnOptionsWithStdioTuple<StdioNull, StdioPipe, StdioPipe>
): ChildProcessByStdio<null, Readable, Readable>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
@param args
List of string arguments.
function spawn(
command: string,
args: readonly string[],
options: SpawnOptionsWithStdioTuple<StdioPipe, StdioNull, StdioNull>
): ChildProcessByStdio<Writable, null, null>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
@param args
List of string arguments.
function spawn(
command: string,
args: readonly string[],
options: SpawnOptionsWithStdioTuple<StdioNull, StdioPipe, StdioNull>
): ChildProcessByStdio<null, Readable, null>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
@param args
List of string arguments.
function spawn(
command: string,
args: readonly string[],
options: SpawnOptionsWithStdioTuple<StdioNull, StdioNull, StdioPipe>
): ChildProcessByStdio<null, null, Readable>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
@param args
List of string arguments.
function spawn(
command: string,
args: readonly string[],
options: SpawnOptionsWithStdioTuple<StdioNull, StdioNull, StdioNull>
): ChildProcessByStdio<null, null, null>;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
@param args
List of string arguments.
function spawn(
command: string,
args: readonly string[],
options: SpawnOptions
): ChildProcess;
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults to an empty array.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
A third argument may be used to specify additional options, with these defaults:
const defaults = { cwd: undefined, env: process.env, };
Use cwd to specify the working directory from which the process is spawned. If not given, the default is to inherit the current working directory. If given, but the path does not exist, the child process emits an ENOENT error and exits immediately. ENOENT is also emitted when the command does not exist.
Use env to specify environment variables that will be visible to the new process, the default is process.env.
undefined values in env will be ignored.
Example of running ls -lh /usr, capturing stdout, stderr, and the exit code:
import { spawn } from 'node:child_process'; const ls = spawn('ls', ['-lh', '/usr']); ls.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }); ls.stderr.on('data', (data) => { console.error(`stderr: ${data}`); }); ls.on('close', (code) => { console.log(`child process exited with code ${code}`); });
Example: A very elaborate way to run ps ax | grep ssh
import { spawn } from 'node:child_process'; const ps = spawn('ps', ['ax']); const grep = spawn('grep', ['ssh']); ps.stdout.on('data', (data) => { grep.stdin.write(data); }); ps.stderr.on('data', (data) => { console.error(`ps stderr: ${data}`); }); ps.on('close', (code) => { if (code !== 0) { console.log(`ps process exited with code ${code}`); } grep.stdin.end(); }); grep.stdout.on('data', (data) => { console.log(data.toString()); }); grep.stderr.on('data', (data) => { console.error(`grep stderr: ${data}`); }); grep.on('close', (code) => { if (code !== 0) { console.log(`grep process exited with code ${code}`); } });
Example of checking for failed spawn:
import { spawn } from 'node:child_process'; const subprocess = spawn('bad_command'); subprocess.on('error', (err) => { console.error('Failed to start subprocess.'); });
Certain platforms (macOS, Linux) will use the value of argv[0] for the process title while others (Windows, SunOS) will use command.
Node.js overwrites argv[0] with process.execPath on startup, so process.argv[0] in a Node.js child process will not match the argv0 parameter passed to spawn from the parent. Retrieve it with the process.argv0 property instead.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { spawn } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const grep = spawn('grep', ['ssh'], { signal }); grep.on('error', (err) => { // This will be called with err being an AbortError if the controller aborts }); controller.abort(); // Stops the child process
@param command
The command to run.
@param args
List of string arguments.
function spawnSync(
command: string
): SpawnSyncReturns<Buffer<ArrayBufferLike>>;
The child_process.spawnSync() method is generally identical to spawn with the exception that the function will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited. If the process intercepts and handles the SIGTERM signal and doesn't exit, the parent process will wait until the child process has exited.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param command
The command to run.
function spawnSync(
command: string,
options: SpawnSyncOptionsWithStringEncoding
): SpawnSyncReturns<string>;
The child_process.spawnSync() method is generally identical to spawn with the exception that the function will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited. If the process intercepts and handles the SIGTERM signal and doesn't exit, the parent process will wait until the child process has exited.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param command
The command to run.
function spawnSync(
command: string,
options: SpawnSyncOptionsWithBufferEncoding
): SpawnSyncReturns<Buffer<ArrayBufferLike>>;
The child_process.spawnSync() method is generally identical to spawn with the exception that the function will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited. If the process intercepts and handles the SIGTERM signal and doesn't exit, the parent process will wait until the child process has exited.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param command
The command to run.
function spawnSync(
command: string,
options?: SpawnSyncOptions
): SpawnSyncReturns<string | Buffer<ArrayBufferLike>>;
The child_process.spawnSync() method is generally identical to spawn with the exception that the function will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited. If the process intercepts and handles the SIGTERM signal and doesn't exit, the parent process will wait until the child process has exited.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param command
The command to run.
function spawnSync(
command: string,
args: readonly string[]
): SpawnSyncReturns<Buffer<ArrayBufferLike>>;
The child_process.spawnSync() method is generally identical to spawn with the exception that the function will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited. If the process intercepts and handles the SIGTERM signal and doesn't exit, the parent process will wait until the child process has exited.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param command
The command to run.
@param args
List of string arguments.
function spawnSync(
command: string,
args: readonly string[],
options: SpawnSyncOptionsWithStringEncoding
): SpawnSyncReturns<string>;
The child_process.spawnSync() method is generally identical to spawn with the exception that the function will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited. If the process intercepts and handles the SIGTERM signal and doesn't exit, the parent process will wait until the child process has exited.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param command
The command to run.
@param args
List of string arguments.
function spawnSync(
command: string,
args: readonly string[],
options: SpawnSyncOptionsWithBufferEncoding
): SpawnSyncReturns<Buffer<ArrayBufferLike>>;
The child_process.spawnSync() method is generally identical to spawn with the exception that the function will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited. If the process intercepts and handles the SIGTERM signal and doesn't exit, the parent process will wait until the child process has exited.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param command
The command to run.
@param args
List of string arguments.
function spawnSync(
command: string,
args?: readonly string[],
options?: SpawnSyncOptions
): SpawnSyncReturns<string | Buffer<ArrayBufferLike>>;
The child_process.spawnSync() method is generally identical to spawn with the exception that the function will not return until the child process has fully closed. When a timeout has been encountered and killSignal is sent, the method won't return until the process has completely exited. If the process intercepts and handles the SIGTERM signal and doesn't exit, the parent process will wait until the child process has exited.
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
@param command
The command to run.
@param args
List of string arguments.

Type definitions

function exec(
command: string,
callback?: (error: null | ExecException, stdout: string, stderr: string) => void
): ChildProcess;
Spawns a shell then executes the command within that shell, buffering any generated output. The command string passed to the exec function is processed directly by the shell and special characters (vary based on shell) need to be dealt with accordingly:
import { exec } from 'node:child_process'; exec('"/path/to/test file/test.sh" arg1 arg2'); // Double quotes are used so that the space in the path is not interpreted as // a delimiter of multiple arguments. exec('echo "The \\$HOME variable is $HOME"'); // The $HOME variable is escaped in the first instance, but not in the second.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If a callback function is provided, it is called with the arguments (error, stdout, stderr). On success, error will be null. On error, error will be an instance of Error. The error.code property will be the exit code of the process. By convention, any exit code other than 0 indicates an error. error.signal will be the signal that terminated the process.
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
import { exec } from 'node:child_process'; exec('cat *.js missing_file | wc -l', (error, stdout, stderr) => { if (error) { console.error(`exec error: ${error}`); return; } console.log(`stdout: ${stdout}`); console.error(`stderr: ${stderr}`); });
If timeout is greater than 0, the parent will send the signal identified by the killSignal property (the default is 'SIGTERM') if the child runs longer than timeout milliseconds.
Unlike the exec(3) POSIX system call, child_process.exec() does not replace the existing process and uses a shell to execute the command.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const exec = util.promisify(child_process.exec); async function lsExample() { const { stdout, stderr } = await exec('ls'); console.log('stdout:', stdout); console.error('stderr:', stderr); } lsExample();
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { exec } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = exec('grep ssh', { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param command
The command to run, with space-separated arguments.
@param callback
called with the output when process terminates.
function exec(
command: string,
options: { encoding: null | 'buffer' } & ExecOptions,
callback?: (error: null | ExecException, stdout: Buffer, stderr: Buffer) => void
): ChildProcess;
Spawns a shell then executes the command within that shell, buffering any generated output. The command string passed to the exec function is processed directly by the shell and special characters (vary based on shell) need to be dealt with accordingly:
import { exec } from 'node:child_process'; exec('"/path/to/test file/test.sh" arg1 arg2'); // Double quotes are used so that the space in the path is not interpreted as // a delimiter of multiple arguments. exec('echo "The \\$HOME variable is $HOME"'); // The $HOME variable is escaped in the first instance, but not in the second.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If a callback function is provided, it is called with the arguments (error, stdout, stderr). On success, error will be null. On error, error will be an instance of Error. The error.code property will be the exit code of the process. By convention, any exit code other than 0 indicates an error. error.signal will be the signal that terminated the process.
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
import { exec } from 'node:child_process'; exec('cat *.js missing_file | wc -l', (error, stdout, stderr) => { if (error) { console.error(`exec error: ${error}`); return; } console.log(`stdout: ${stdout}`); console.error(`stderr: ${stderr}`); });
If timeout is greater than 0, the parent will send the signal identified by the killSignal property (the default is 'SIGTERM') if the child runs longer than timeout milliseconds.
Unlike the exec(3) POSIX system call, child_process.exec() does not replace the existing process and uses a shell to execute the command.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const exec = util.promisify(child_process.exec); async function lsExample() { const { stdout, stderr } = await exec('ls'); console.log('stdout:', stdout); console.error('stderr:', stderr); } lsExample();
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { exec } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = exec('grep ssh', { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param command
The command to run, with space-separated arguments.
@param callback
called with the output when process terminates.
function exec(
command: string,
options: { encoding: BufferEncoding } & ExecOptions,
callback?: (error: null | ExecException, stdout: string, stderr: string) => void
): ChildProcess;
Spawns a shell then executes the command within that shell, buffering any generated output. The command string passed to the exec function is processed directly by the shell and special characters (vary based on shell) need to be dealt with accordingly:
import { exec } from 'node:child_process'; exec('"/path/to/test file/test.sh" arg1 arg2'); // Double quotes are used so that the space in the path is not interpreted as // a delimiter of multiple arguments. exec('echo "The \\$HOME variable is $HOME"'); // The $HOME variable is escaped in the first instance, but not in the second.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If a callback function is provided, it is called with the arguments (error, stdout, stderr). On success, error will be null. On error, error will be an instance of Error. The error.code property will be the exit code of the process. By convention, any exit code other than 0 indicates an error. error.signal will be the signal that terminated the process.
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
import { exec } from 'node:child_process'; exec('cat *.js missing_file | wc -l', (error, stdout, stderr) => { if (error) { console.error(`exec error: ${error}`); return; } console.log(`stdout: ${stdout}`); console.error(`stderr: ${stderr}`); });
If timeout is greater than 0, the parent will send the signal identified by the killSignal property (the default is 'SIGTERM') if the child runs longer than timeout milliseconds.
Unlike the exec(3) POSIX system call, child_process.exec() does not replace the existing process and uses a shell to execute the command.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const exec = util.promisify(child_process.exec); async function lsExample() { const { stdout, stderr } = await exec('ls'); console.log('stdout:', stdout); console.error('stderr:', stderr); } lsExample();
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { exec } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = exec('grep ssh', { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param command
The command to run, with space-separated arguments.
@param callback
called with the output when process terminates.
function exec(
command: string,
options: { encoding: BufferEncoding } & ExecOptions,
callback?: (error: null | ExecException, stdout: string | Buffer<ArrayBufferLike>, stderr: string | Buffer<ArrayBufferLike>) => void
): ChildProcess;
Spawns a shell then executes the command within that shell, buffering any generated output. The command string passed to the exec function is processed directly by the shell and special characters (vary based on shell) need to be dealt with accordingly:
import { exec } from 'node:child_process'; exec('"/path/to/test file/test.sh" arg1 arg2'); // Double quotes are used so that the space in the path is not interpreted as // a delimiter of multiple arguments. exec('echo "The \\$HOME variable is $HOME"'); // The $HOME variable is escaped in the first instance, but not in the second.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If a callback function is provided, it is called with the arguments (error, stdout, stderr). On success, error will be null. On error, error will be an instance of Error. The error.code property will be the exit code of the process. By convention, any exit code other than 0 indicates an error. error.signal will be the signal that terminated the process.
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
import { exec } from 'node:child_process'; exec('cat *.js missing_file | wc -l', (error, stdout, stderr) => { if (error) { console.error(`exec error: ${error}`); return; } console.log(`stdout: ${stdout}`); console.error(`stderr: ${stderr}`); });
If timeout is greater than 0, the parent will send the signal identified by the killSignal property (the default is 'SIGTERM') if the child runs longer than timeout milliseconds.
Unlike the exec(3) POSIX system call, child_process.exec() does not replace the existing process and uses a shell to execute the command.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const exec = util.promisify(child_process.exec); async function lsExample() { const { stdout, stderr } = await exec('ls'); console.log('stdout:', stdout); console.error('stderr:', stderr); } lsExample();
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { exec } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = exec('grep ssh', { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param command
The command to run, with space-separated arguments.
@param callback
called with the output when process terminates.
function exec(
command: string,
options: ExecOptions,
callback?: (error: null | ExecException, stdout: string, stderr: string) => void
): ChildProcess;
Spawns a shell then executes the command within that shell, buffering any generated output. The command string passed to the exec function is processed directly by the shell and special characters (vary based on shell) need to be dealt with accordingly:
import { exec } from 'node:child_process'; exec('"/path/to/test file/test.sh" arg1 arg2'); // Double quotes are used so that the space in the path is not interpreted as // a delimiter of multiple arguments. exec('echo "The \\$HOME variable is $HOME"'); // The $HOME variable is escaped in the first instance, but not in the second.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If a callback function is provided, it is called with the arguments (error, stdout, stderr). On success, error will be null. On error, error will be an instance of Error. The error.code property will be the exit code of the process. By convention, any exit code other than 0 indicates an error. error.signal will be the signal that terminated the process.
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
import { exec } from 'node:child_process'; exec('cat *.js missing_file | wc -l', (error, stdout, stderr) => { if (error) { console.error(`exec error: ${error}`); return; } console.log(`stdout: ${stdout}`); console.error(`stderr: ${stderr}`); });
If timeout is greater than 0, the parent will send the signal identified by the killSignal property (the default is 'SIGTERM') if the child runs longer than timeout milliseconds.
Unlike the exec(3) POSIX system call, child_process.exec() does not replace the existing process and uses a shell to execute the command.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const exec = util.promisify(child_process.exec); async function lsExample() { const { stdout, stderr } = await exec('ls'); console.log('stdout:', stdout); console.error('stderr:', stderr); } lsExample();
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { exec } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = exec('grep ssh', { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param command
The command to run, with space-separated arguments.
@param callback
called with the output when process terminates.
function exec(
command: string,
options: undefined | null | ObjectEncodingOptions & ExecOptions,
callback?: (error: null | ExecException, stdout: string | Buffer<ArrayBufferLike>, stderr: string | Buffer<ArrayBufferLike>) => void
): ChildProcess;
Spawns a shell then executes the command within that shell, buffering any generated output. The command string passed to the exec function is processed directly by the shell and special characters (vary based on shell) need to be dealt with accordingly:
import { exec } from 'node:child_process'; exec('"/path/to/test file/test.sh" arg1 arg2'); // Double quotes are used so that the space in the path is not interpreted as // a delimiter of multiple arguments. exec('echo "The \\$HOME variable is $HOME"'); // The $HOME variable is escaped in the first instance, but not in the second.
Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If a callback function is provided, it is called with the arguments (error, stdout, stderr). On success, error will be null. On error, error will be an instance of Error. The error.code property will be the exit code of the process. By convention, any exit code other than 0 indicates an error. error.signal will be the signal that terminated the process.
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
import { exec } from 'node:child_process'; exec('cat *.js missing_file | wc -l', (error, stdout, stderr) => { if (error) { console.error(`exec error: ${error}`); return; } console.log(`stdout: ${stdout}`); console.error(`stderr: ${stderr}`); });
If timeout is greater than 0, the parent will send the signal identified by the killSignal property (the default is 'SIGTERM') if the child runs longer than timeout milliseconds.
Unlike the exec(3) POSIX system call, child_process.exec() does not replace the existing process and uses a shell to execute the command.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const exec = util.promisify(child_process.exec); async function lsExample() { const { stdout, stderr } = await exec('ls'); console.log('stdout:', stdout); console.error('stderr:', stderr); } lsExample();
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { exec } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = exec('grep ssh', { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param command
The command to run, with space-separated arguments.
@param callback
called with the output when process terminates.
namespace exec
function execFile(
file: string
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
function execFile(
file: string,
options: undefined | null | ObjectEncodingOptions & ExecFileOptions
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
function execFile(
file: string,
args?: null | readonly string[]
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
function execFile(
file: string,
args: undefined | null | readonly string[],
options: undefined | null | ObjectEncodingOptions & ExecFileOptions
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
function execFile(
file: string,
callback: (error: null | ExecFileException, stdout: string, stderr: string) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
args: undefined | null | readonly string[],
callback: (error: null | ExecFileException, stdout: string, stderr: string) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
options: ExecFileOptionsWithBufferEncoding,
callback: (error: null | ExecFileException, stdout: Buffer, stderr: Buffer) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
args: undefined | null | readonly string[],
options: ExecFileOptionsWithBufferEncoding,
callback: (error: null | ExecFileException, stdout: Buffer, stderr: Buffer) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
options: ExecFileOptionsWithStringEncoding,
callback: (error: null | ExecFileException, stdout: string, stderr: string) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
args: undefined | null | readonly string[],
options: ExecFileOptionsWithStringEncoding,
callback: (error: null | ExecFileException, stdout: string, stderr: string) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
options: ExecFileOptionsWithOtherEncoding,
callback: (error: null | ExecFileException, stdout: string | Buffer<ArrayBufferLike>, stderr: string | Buffer<ArrayBufferLike>) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
args: undefined | null | readonly string[],
options: ExecFileOptionsWithOtherEncoding,
callback: (error: null | ExecFileException, stdout: string | Buffer<ArrayBufferLike>, stderr: string | Buffer<ArrayBufferLike>) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
options: ExecFileOptions,
callback: (error: null | ExecFileException, stdout: string, stderr: string) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
args: undefined | null | readonly string[],
options: ExecFileOptions,
callback: (error: null | ExecFileException, stdout: string, stderr: string) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
options: undefined | null | ObjectEncodingOptions & ExecFileOptions,
callback: undefined | null | (error: null | ExecFileException, stdout: string | Buffer<ArrayBufferLike>, stderr: string | Buffer<ArrayBufferLike>) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param callback
Called with the output when process terminates.
function execFile(
file: string,
args: undefined | null | readonly string[],
options: undefined | null | ObjectEncodingOptions & ExecFileOptions,
callback: undefined | null | (error: null | ExecFileException, stdout: string | Buffer<ArrayBufferLike>, stderr: string | Buffer<ArrayBufferLike>) => void
): ChildProcess;
The child_process.execFile() function is similar to exec except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec.
The same options as exec are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.
import { execFile } from 'node:child_process'; const child = execFile('node', ['--version'], (error, stdout, stderr) => { if (error) { throw error; } console.log(stdout); });
The stdout and stderr arguments passed to the callback will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.
If this method is invoked as its util.promisify() ed version, it returns a Promise for an Object with stdout and stderr properties. The returned ChildProcess instance is attached to the Promise as a child property. In case of an error (including any error resulting in an exit code other than 0), a rejected promise is returned, with the same error object given in the callback, but with two additional properties stdout and stderr.
import util from 'node:util'; import child_process from 'node:child_process'; const execFile = util.promisify(child_process.execFile); async function getVersion() { const { stdout } = await execFile('node', ['--version']); console.log(stdout); } getVersion();
If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.
If the signal option is enabled, calling .abort() on the corresponding AbortController is similar to calling .kill() on the child process except the error passed to the callback will be an AbortError:
import { execFile } from 'node:child_process'; const controller = new AbortController(); const { signal } = controller; const child = execFile('node', ['--version'], { signal }, (error) => { console.error(error); // an AbortError }); controller.abort();
@param file
The name or path of the executable file to run.
@param args
List of string arguments.
@param callback
Called with the output when process terminates.
namespace execFile
interface ChildProcessByStdio<I extends null | Writable, O extends null | Readable, E extends null | Readable>
Instances of the ChildProcess represent spawned child processes.
Instances of ChildProcess are not intended to be created directly. Rather, use the spawn, exec,execFile, or fork methods to create instances of ChildProcess.
- readonly channel?: null | Pipe
  The subprocess.channel property is a reference to the child's IPC channel. If no IPC channel exists, this property is undefined.
- readonly connected: boolean
  The subprocess.connected property indicates whether it is still possible to send and receive messages from a child process. When subprocess.connected is false, it is no longer possible to send or receive messages.
- readonly exitCode: null | number
  The subprocess.exitCode property indicates the exit code of the child process. If the child process is still running, the field will be null.
- readonly killed: boolean
  The subprocess.killed property indicates whether the child process successfully received a signal from subprocess.kill(). The killed property does not indicate that the child process has been terminated.
- readonly pid?: number
  Returns the process identifier (PID) of the child process. If the child process fails to spawn due to errors, then the value is undefined and error is emitted.
  import { spawn } from 'node:child_process'; const grep = spawn('grep', ['ssh']); console.log(`Spawned child pid: ${grep.pid}`); grep.stdin.end();
- readonly signalCode: null | Signals
  The subprocess.signalCode property indicates the signal received by the child process if any, else null.
- readonly spawnargs: string[]
  The subprocess.spawnargs property represents the full list of command-line arguments the child process was launched with.
- readonly spawnfile: string
  The subprocess.spawnfile property indicates the executable file name of the child process that is launched.
  For fork, its value will be equal to process.execPath. For spawn, its value will be the name of the executable file. For exec, its value will be the name of the shell in which the child process is launched.
- stderr: E
  A Readable Stream that represents the child process's stderr.
  If the child was spawned with stdio[2] set to anything other than 'pipe', then this will be null.
  subprocess.stderr is an alias for subprocess.stdio[2]. Both properties will refer to the same value.
  The subprocess.stderr property can be null or undefined if the child process could not be successfully spawned.
- stdin: I
  A Writable Stream that represents the child process's stdin.
  If a child process waits to read all of its input, the child will not continue until this stream has been closed via end().
  If the child was spawned with stdio[0] set to anything other than 'pipe', then this will be null.
  subprocess.stdin is an alias for subprocess.stdio[0]. Both properties will refer to the same value.
  The subprocess.stdin property can be null or undefined if the child process could not be successfully spawned.
- readonly stdio: [I, O, E, undefined | null | Writable | Readable, undefined | null | Writable | Readable]
  A sparse array of pipes to the child process, corresponding with positions in the stdio option passed to spawn that have been set to the value 'pipe'. subprocess.stdio[0], subprocess.stdio[1], and subprocess.stdio[2] are also available as subprocess.stdin, subprocess.stdout, and subprocess.stderr, respectively.
  In the following example, only the child's fd 1 (stdout) is configured as a pipe, so only the parent's subprocess.stdio[1] is a stream, all other values in the array are null.
  import assert from 'node:assert'; import fs from 'node:fs'; import child_process from 'node:child_process'; const subprocess = child_process.spawn('ls', { stdio: [ 0, // Use parent's stdin for child. 'pipe', // Pipe child's stdout to parent. fs.openSync('err.out', 'w'), // Direct child's stderr to a file. ], }); assert.strictEqual(subprocess.stdio[0], null); assert.strictEqual(subprocess.stdio[0], subprocess.stdin); assert(subprocess.stdout); assert.strictEqual(subprocess.stdio[1], subprocess.stdout); assert.strictEqual(subprocess.stdio[2], null); assert.strictEqual(subprocess.stdio[2], subprocess.stderr);
  The subprocess.stdio property can be undefined if the child process could not be successfully spawned.
- stdout: O
  A Readable Stream that represents the child process's stdout.
  If the child was spawned with stdio[1] set to anything other than 'pipe', then this will be null.
  subprocess.stdout is an alias for subprocess.stdio[1]. Both properties will refer to the same value.
  import { spawn } from 'node:child_process'; const subprocess = spawn('ls'); subprocess.stdout.on('data', (data) => { console.log(`Received chunk ${data}`); });
  The subprocess.stdout property can be null or undefined if the child process could not be successfully spawned.
- [events.captureRejectionSymbol]<K>(
  error: Error,
  event: string | symbol,
  ...args: AnyRest
  ): void;
- [Symbol.dispose](): void;
  Calls ChildProcess.kill with 'SIGTERM'.
- addListener(
  event: string,
  listener: (...args: any[]) => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'close',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'disconnect',
  listener: () => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'error',
  listener: (err: Error) => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'exit',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'message',
  listener: (message: Serializable, sendHandle: SendHandle) => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'spawn',
  listener: () => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
- disconnect(): void;
  Closes the IPC channel between parent and child, allowing the child to exit gracefully once there are no other connections keeping it alive. After calling this method the subprocess.connected and process.connected properties in both the parent and child (respectively) will be set to false, and it will be no longer possible to pass messages between the processes.
  The 'disconnect' event will be emitted when there are no messages in the process of being received. This will most often be triggered immediately after calling subprocess.disconnect().
  When the child process is a Node.js instance (e.g. spawned using fork), the process.disconnect() method can be invoked within the child process to close the IPC channel as well.
- emit(
  event: string | symbol,
  ...args: any[]
  ): boolean;
  Synchronously calls each of the listeners registered for the event named eventName, in the order they were registered, passing the supplied arguments to each.
  Returns true if the event had listeners, false otherwise.
  import { EventEmitter } from 'node:events'; const myEmitter = new EventEmitter(); // First listener myEmitter.on('event', function firstListener() { console.log('Helloooo! first listener'); }); // Second listener myEmitter.on('event', function secondListener(arg1, arg2) { console.log(`event with parameters ${arg1}, ${arg2} in second listener`); }); // Third listener myEmitter.on('event', function thirdListener(...args) { const parameters = args.join(', '); console.log(`event with parameters ${parameters} in third listener`); }); console.log(myEmitter.listeners('event')); myEmitter.emit('event', 1, 2, 3, 4, 5); // Prints: // [ // [Function: firstListener], // [Function: secondListener], // [Function: thirdListener] // ] // Helloooo! first listener // event with parameters 1, 2 in second listener // event with parameters 1, 2, 3, 4, 5 in third listener
  emit(
  event: 'close',
  code: null | number,
  signal: null | Signals
  ): boolean;
  emit(
  event: 'disconnect'
  ): boolean;
  emit(
  event: 'error',
  err: Error
  ): boolean;
  emit(
  event: 'exit',
  code: null | number,
  signal: null | Signals
  ): boolean;
  emit(
  event: 'message',
  message: Serializable,
  sendHandle: SendHandle
  ): boolean;
  emit(
  event: 'spawn',
  listener: () => void
  ): boolean;
- eventNames(): string | symbol[];
  Returns an array listing the events for which the emitter has registered listeners. The values in the array are strings or Symbols.
  import { EventEmitter } from 'node:events'; const myEE = new EventEmitter(); myEE.on('foo', () => {}); myEE.on('bar', () => {}); const sym = Symbol('symbol'); myEE.on(sym, () => {}); console.log(myEE.eventNames()); // Prints: [ 'foo', 'bar', Symbol(symbol) ]
- getMaxListeners(): number;
  Returns the current max listener value for the EventEmitter which is either set by emitter.setMaxListeners(n) or defaults to EventEmitter.defaultMaxListeners.
- kill(
  signal?: number | Signals
  ): boolean;
  The subprocess.kill() method sends a signal to the child process. If no argument is given, the process will be sent the 'SIGTERM' signal. See signal(7) for a list of available signals. This function returns true if kill(2) succeeds, and false otherwise.
  import { spawn } from 'node:child_process'; const grep = spawn('grep', ['ssh']); grep.on('close', (code, signal) => { console.log( `child process terminated due to receipt of signal ${signal}`); }); // Send SIGHUP to process. grep.kill('SIGHUP');
  The ChildProcess object may emit an 'error' event if the signal cannot be delivered. Sending a signal to a child process that has already exited is not an error but may have unforeseen consequences. Specifically, if the process identifier (PID) has been reassigned to another process, the signal will be delivered to that process instead which can have unexpected results.
  While the function is called kill, the signal delivered to the child process may not actually terminate the process.
  See kill(2) for reference.
  On Windows, where POSIX signals do not exist, the signal argument will be ignored, and the process will be killed forcefully and abruptly (similar to 'SIGKILL'). See Signal Events for more details.
  On Linux, child processes of child processes will not be terminated when attempting to kill their parent. This is likely to happen when running a new process in a shell or with the use of the shell option of ChildProcess:
  'use strict'; import { spawn } from 'node:child_process'; const subprocess = spawn( 'sh', [ '-c', `node -e "setInterval(() => { console.log(process.pid, 'is alive') }, 500);"`, ], { stdio: ['inherit', 'inherit', 'inherit'], }, ); setTimeout(() => { subprocess.kill(); // Does not terminate the Node.js process in the shell. }, 2000);
- listenerCount<K>(
  eventName: string | symbol,
  listener?: Function
  ): number;
  Returns the number of listeners listening for the event named eventName. If listener is provided, it will return how many times the listener is found in the list of the listeners of the event.
  @param eventName
  The name of the event being listened for
  @param listener
  The event handler function
- listeners<K>(
  eventName: string | symbol
  ): Function[];
  Returns a copy of the array of listeners for the event named eventName.
  server.on('connection', (stream) => { console.log('someone connected!'); }); console.log(util.inspect(server.listeners('connection'))); // Prints: [ [Function] ]
- off<K>(
  eventName: string | symbol,
  listener: (...args: any[]) => void
  ): this;
  Alias for emitter.removeListener().
- on(
  event: string,
  listener: (...args: any[]) => void
  ): this;
  Adds the listener function to the end of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventName and listener will result in the listener being added, and called, multiple times.
  server.on('connection', (stream) => { console.log('someone connected!'); });
  Returns a reference to the EventEmitter, so that calls can be chained.
  By default, event listeners are invoked in the order they are added. The emitter.prependListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.
  import { EventEmitter } from 'node:events'; const myEE = new EventEmitter(); myEE.on('foo', () => console.log('a')); myEE.prependListener('foo', () => console.log('b')); myEE.emit('foo'); // Prints: // b // a
  @param listener
  The callback function
  on(
  event: 'close',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  on(
  event: 'disconnect',
  listener: () => void
  ): this;
  on(
  event: 'error',
  listener: (err: Error) => void
  ): this;
  on(
  event: 'exit',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  on(
  event: 'message',
  listener: (message: Serializable, sendHandle: SendHandle) => void
  ): this;
  on(
  event: 'spawn',
  listener: () => void
  ): this;
- once(
  event: string,
  listener: (...args: any[]) => void
  ): this;
  Adds a one-time listener function for the event named eventName. The next time eventName is triggered, this listener is removed and then invoked.
  server.once('connection', (stream) => { console.log('Ah, we have our first user!'); });
  Returns a reference to the EventEmitter, so that calls can be chained.
  By default, event listeners are invoked in the order they are added. The emitter.prependOnceListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.
  import { EventEmitter } from 'node:events'; const myEE = new EventEmitter(); myEE.once('foo', () => console.log('a')); myEE.prependOnceListener('foo', () => console.log('b')); myEE.emit('foo'); // Prints: // b // a
  @param listener
  The callback function
  once(
  event: 'close',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  once(
  event: 'disconnect',
  listener: () => void
  ): this;
  once(
  event: 'error',
  listener: (err: Error) => void
  ): this;
  once(
  event: 'exit',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  once(
  event: 'message',
  listener: (message: Serializable, sendHandle: SendHandle) => void
  ): this;
  once(
  event: 'spawn',
  listener: () => void
  ): this;
- prependListener(
  event: string,
  listener: (...args: any[]) => void
  ): this;
  Adds the listener function to the beginning of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventName and listener will result in the listener being added, and called, multiple times.
  server.prependListener('connection', (stream) => { console.log('someone connected!'); });
  Returns a reference to the EventEmitter, so that calls can be chained.
  @param listener
  The callback function
  prependListener(
  event: 'close',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  prependListener(
  event: 'disconnect',
  listener: () => void
  ): this;
  prependListener(
  event: 'error',
  listener: (err: Error) => void
  ): this;
  prependListener(
  event: 'exit',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  prependListener(
  event: 'message',
  listener: (message: Serializable, sendHandle: SendHandle) => void
  ): this;
  prependListener(
  event: 'spawn',
  listener: () => void
  ): this;
- prependOnceListener(
  event: string,
  listener: (...args: any[]) => void
  ): this;
  Adds a one-timelistener function for the event named eventName to the beginning of the listeners array. The next time eventName is triggered, this listener is removed, and then invoked.
  server.prependOnceListener('connection', (stream) => { console.log('Ah, we have our first user!'); });
  Returns a reference to the EventEmitter, so that calls can be chained.
  @param listener
  The callback function
  prependOnceListener(
  event: 'close',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  prependOnceListener(
  event: 'disconnect',
  listener: () => void
  ): this;
  prependOnceListener(
  event: 'error',
  listener: (err: Error) => void
  ): this;
  prependOnceListener(
  event: 'exit',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  prependOnceListener(
  event: 'message',
  listener: (message: Serializable, sendHandle: SendHandle) => void
  ): this;
  prependOnceListener(
  event: 'spawn',
  listener: () => void
  ): this;
- rawListeners<K>(
  eventName: string | symbol
  ): Function[];
  Returns a copy of the array of listeners for the event named eventName, including any wrappers (such as those created by .once()).
  import { EventEmitter } from 'node:events'; const emitter = new EventEmitter(); emitter.once('log', () => console.log('log once')); // Returns a new Array with a function `onceWrapper` which has a property // `listener` which contains the original listener bound above const listeners = emitter.rawListeners('log'); const logFnWrapper = listeners[0]; // Logs "log once" to the console and does not unbind the `once` event logFnWrapper.listener(); // Logs "log once" to the console and removes the listener logFnWrapper(); emitter.on('log', () => console.log('log persistently')); // Will return a new Array with a single function bound by `.on()` above const newListeners = emitter.rawListeners('log'); // Logs "log persistently" twice newListeners[0](); emitter.emit('log');
- ref(): void;
  Calling subprocess.ref() after making a call to subprocess.unref() will restore the removed reference count for the child process, forcing the parent to wait for the child to exit before exiting itself.
  import { spawn } from 'node:child_process'; const subprocess = spawn(process.argv[0], ['child_program.js'], { detached: true, stdio: 'ignore', }); subprocess.unref(); subprocess.ref();
- removeAllListeners(
  eventName?: string | symbol
  ): this;
  Removes all listeners, or those of the specified eventName.
  It is bad practice to remove listeners added elsewhere in the code, particularly when the EventEmitter instance was created by some other component or module (e.g. sockets or file streams).
  Returns a reference to the EventEmitter, so that calls can be chained.
- removeListener<K>(
  eventName: string | symbol,
  listener: (...args: any[]) => void
  ): this;
  Removes the specified listener from the listener array for the event named eventName.
  const callback = (stream) => { console.log('someone connected!'); }; server.on('connection', callback); // ... server.removeListener('connection', callback);
  removeListener() will remove, at most, one instance of a listener from the listener array. If any single listener has been added multiple times to the listener array for the specified eventName, then removeListener() must be called multiple times to remove each instance.
  Once an event is emitted, all listeners attached to it at the time of emitting are called in order. This implies that any removeListener() or removeAllListeners() calls after emitting and before the last listener finishes execution will not remove them fromemit() in progress. Subsequent events behave as expected.
  import { EventEmitter } from 'node:events'; class MyEmitter extends EventEmitter {} const myEmitter = new MyEmitter(); const callbackA = () => { console.log('A'); myEmitter.removeListener('event', callbackB); }; const callbackB = () => { console.log('B'); }; myEmitter.on('event', callbackA); myEmitter.on('event', callbackB); // callbackA removes listener callbackB but it will still be called. // Internal listener array at time of emit [callbackA, callbackB] myEmitter.emit('event'); // Prints: // A // B // callbackB is now removed. // Internal listener array [callbackA] myEmitter.emit('event'); // Prints: // A
  Because listeners are managed using an internal array, calling this will change the position indices of any listener registered after the listener being removed. This will not impact the order in which listeners are called, but it means that any copies of the listener array as returned by the emitter.listeners() method will need to be recreated.
  When a single function has been added as a handler multiple times for a single event (as in the example below), removeListener() will remove the most recently added instance. In the example the once('ping') listener is removed:
  import { EventEmitter } from 'node:events'; const ee = new EventEmitter(); function pong() { console.log('pong'); } ee.on('ping', pong); ee.once('ping', pong); ee.removeListener('ping', pong); ee.emit('ping'); ee.emit('ping');
  Returns a reference to the EventEmitter, so that calls can be chained.
- send(
  message: Serializable,
  callback?: (error: null | Error) => void
  ): boolean;
  When an IPC channel has been established between the parent and child ( i.e. when using fork), the subprocess.send() method can be used to send messages to the child process. When the child process is a Node.js instance, these messages can be received via the 'message' event.
  The message goes through serialization and parsing. The resulting message might not be the same as what is originally sent.
  For example, in the parent script:
  import cp from 'node:child_process'; const n = cp.fork(`${__dirname}/sub.js`); n.on('message', (m) => { console.log('PARENT got message:', m); }); // Causes the child to print: CHILD got message: { hello: 'world' } n.send({ hello: 'world' });
  And then the child script, 'sub.js' might look like this:
  process.on('message', (m) => { console.log('CHILD got message:', m); }); // Causes the parent to print: PARENT got message: { foo: 'bar', baz: null } process.send({ foo: 'bar', baz: NaN });
  Child Node.js processes will have a process.send() method of their own that allows the child to send messages back to the parent.
  There is a special case when sending a {cmd: 'NODE_foo'} message. Messages containing a NODE_ prefix in the cmd property are reserved for use within Node.js core and will not be emitted in the child's 'message' event. Rather, such messages are emitted using the 'internalMessage' event and are consumed internally by Node.js. Applications should avoid using such messages or listening for 'internalMessage' events as it is subject to change without notice.
  The optional sendHandle argument that may be passed to subprocess.send() is for passing a TCP server or socket object to the child process. The child will receive the object as the second argument passed to the callback function registered on the 'message' event. Any data that is received and buffered in the socket will not be sent to the child. Sending IPC sockets is not supported on Windows.
  The optional callback is a function that is invoked after the message is sent but before the child may have received it. The function is called with a single argument: null on success, or an Error object on failure.
  If no callback function is provided and the message cannot be sent, an 'error' event will be emitted by the ChildProcess object. This can happen, for instance, when the child process has already exited.
  subprocess.send() will return false if the channel has closed or when the backlog of unsent messages exceeds a threshold that makes it unwise to send more. Otherwise, the method returns true. The callback function can be used to implement flow control.
  Example: sending a server object
  The sendHandle argument can be used, for instance, to pass the handle of a TCP server object to the child process as illustrated in the example below:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const subprocess = fork('subprocess.js'); // Open up the server object and send the handle. const server = createServer(); server.on('connection', (socket) => { socket.end('handled by parent'); }); server.listen(1337, () => { subprocess.send('server', server); });
  The child would then receive the server object as:
  process.on('message', (m, server) => { if (m === 'server') { server.on('connection', (socket) => { socket.end('handled by child'); }); } });
  Once the server is now shared between the parent and child, some connections can be handled by the parent and some by the child.
  While the example above uses a server created using the node:net module, node:dgram module servers use exactly the same workflow with the exceptions of listening on a 'message' event instead of 'connection' and using server.bind() instead of server.listen(). This is, however, only supported on Unix platforms.
  Example: sending a socket object
  Similarly, the sendHandler argument can be used to pass the handle of a socket to the child process. The example below spawns two children that each handle connections with "normal" or "special" priority:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const normal = fork('subprocess.js', ['normal']); const special = fork('subprocess.js', ['special']); // Open up the server and send sockets to child. Use pauseOnConnect to prevent // the sockets from being read before they are sent to the child process. const server = createServer({ pauseOnConnect: true }); server.on('connection', (socket) => { // If this is special priority... if (socket.remoteAddress === '74.125.127.100') { special.send('socket', socket); return; } // This is normal priority. normal.send('socket', socket); }); server.listen(1337);
  The subprocess.js would receive the socket handle as the second argument passed to the event callback function:
  process.on('message', (m, socket) => { if (m === 'socket') { if (socket) { // Check that the client socket exists. // It is possible for the socket to be closed between the time it is // sent and the time it is received in the child process. socket.end(`Request handled with ${process.argv[2]} priority`); } } });
  Do not use .maxConnections on a socket that has been passed to a subprocess. The parent cannot track when the socket is destroyed.
  Any 'message' handlers in the subprocess should verify that socket exists, as the connection may have been closed during the time it takes to send the connection to the child.
  send(
  message: Serializable,
  sendHandle?: SendHandle,
  callback?: (error: null | Error) => void
  ): boolean;
  When an IPC channel has been established between the parent and child ( i.e. when using fork), the subprocess.send() method can be used to send messages to the child process. When the child process is a Node.js instance, these messages can be received via the 'message' event.
  The message goes through serialization and parsing. The resulting message might not be the same as what is originally sent.
  For example, in the parent script:
  import cp from 'node:child_process'; const n = cp.fork(`${__dirname}/sub.js`); n.on('message', (m) => { console.log('PARENT got message:', m); }); // Causes the child to print: CHILD got message: { hello: 'world' } n.send({ hello: 'world' });
  And then the child script, 'sub.js' might look like this:
  process.on('message', (m) => { console.log('CHILD got message:', m); }); // Causes the parent to print: PARENT got message: { foo: 'bar', baz: null } process.send({ foo: 'bar', baz: NaN });
  Child Node.js processes will have a process.send() method of their own that allows the child to send messages back to the parent.
  There is a special case when sending a {cmd: 'NODE_foo'} message. Messages containing a NODE_ prefix in the cmd property are reserved for use within Node.js core and will not be emitted in the child's 'message' event. Rather, such messages are emitted using the 'internalMessage' event and are consumed internally by Node.js. Applications should avoid using such messages or listening for 'internalMessage' events as it is subject to change without notice.
  The optional sendHandle argument that may be passed to subprocess.send() is for passing a TCP server or socket object to the child process. The child will receive the object as the second argument passed to the callback function registered on the 'message' event. Any data that is received and buffered in the socket will not be sent to the child. Sending IPC sockets is not supported on Windows.
  The optional callback is a function that is invoked after the message is sent but before the child may have received it. The function is called with a single argument: null on success, or an Error object on failure.
  If no callback function is provided and the message cannot be sent, an 'error' event will be emitted by the ChildProcess object. This can happen, for instance, when the child process has already exited.
  subprocess.send() will return false if the channel has closed or when the backlog of unsent messages exceeds a threshold that makes it unwise to send more. Otherwise, the method returns true. The callback function can be used to implement flow control.
  Example: sending a server object
  The sendHandle argument can be used, for instance, to pass the handle of a TCP server object to the child process as illustrated in the example below:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const subprocess = fork('subprocess.js'); // Open up the server object and send the handle. const server = createServer(); server.on('connection', (socket) => { socket.end('handled by parent'); }); server.listen(1337, () => { subprocess.send('server', server); });
  The child would then receive the server object as:
  process.on('message', (m, server) => { if (m === 'server') { server.on('connection', (socket) => { socket.end('handled by child'); }); } });
  Once the server is now shared between the parent and child, some connections can be handled by the parent and some by the child.
  While the example above uses a server created using the node:net module, node:dgram module servers use exactly the same workflow with the exceptions of listening on a 'message' event instead of 'connection' and using server.bind() instead of server.listen(). This is, however, only supported on Unix platforms.
  Example: sending a socket object
  Similarly, the sendHandler argument can be used to pass the handle of a socket to the child process. The example below spawns two children that each handle connections with "normal" or "special" priority:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const normal = fork('subprocess.js', ['normal']); const special = fork('subprocess.js', ['special']); // Open up the server and send sockets to child. Use pauseOnConnect to prevent // the sockets from being read before they are sent to the child process. const server = createServer({ pauseOnConnect: true }); server.on('connection', (socket) => { // If this is special priority... if (socket.remoteAddress === '74.125.127.100') { special.send('socket', socket); return; } // This is normal priority. normal.send('socket', socket); }); server.listen(1337);
  The subprocess.js would receive the socket handle as the second argument passed to the event callback function:
  process.on('message', (m, socket) => { if (m === 'socket') { if (socket) { // Check that the client socket exists. // It is possible for the socket to be closed between the time it is // sent and the time it is received in the child process. socket.end(`Request handled with ${process.argv[2]} priority`); } } });
  Do not use .maxConnections on a socket that has been passed to a subprocess. The parent cannot track when the socket is destroyed.
  Any 'message' handlers in the subprocess should verify that socket exists, as the connection may have been closed during the time it takes to send the connection to the child.
  @param sendHandle
  undefined, or a net.Socket, net.Server, or dgram.Socket object.
  send(
  message: Serializable,
  sendHandle?: SendHandle,
  options?: MessageOptions,
  callback?: (error: null | Error) => void
  ): boolean;
  When an IPC channel has been established between the parent and child ( i.e. when using fork), the subprocess.send() method can be used to send messages to the child process. When the child process is a Node.js instance, these messages can be received via the 'message' event.
  The message goes through serialization and parsing. The resulting message might not be the same as what is originally sent.
  For example, in the parent script:
  import cp from 'node:child_process'; const n = cp.fork(`${__dirname}/sub.js`); n.on('message', (m) => { console.log('PARENT got message:', m); }); // Causes the child to print: CHILD got message: { hello: 'world' } n.send({ hello: 'world' });
  And then the child script, 'sub.js' might look like this:
  process.on('message', (m) => { console.log('CHILD got message:', m); }); // Causes the parent to print: PARENT got message: { foo: 'bar', baz: null } process.send({ foo: 'bar', baz: NaN });
  Child Node.js processes will have a process.send() method of their own that allows the child to send messages back to the parent.
  There is a special case when sending a {cmd: 'NODE_foo'} message. Messages containing a NODE_ prefix in the cmd property are reserved for use within Node.js core and will not be emitted in the child's 'message' event. Rather, such messages are emitted using the 'internalMessage' event and are consumed internally by Node.js. Applications should avoid using such messages or listening for 'internalMessage' events as it is subject to change without notice.
  The optional sendHandle argument that may be passed to subprocess.send() is for passing a TCP server or socket object to the child process. The child will receive the object as the second argument passed to the callback function registered on the 'message' event. Any data that is received and buffered in the socket will not be sent to the child. Sending IPC sockets is not supported on Windows.
  The optional callback is a function that is invoked after the message is sent but before the child may have received it. The function is called with a single argument: null on success, or an Error object on failure.
  If no callback function is provided and the message cannot be sent, an 'error' event will be emitted by the ChildProcess object. This can happen, for instance, when the child process has already exited.
  subprocess.send() will return false if the channel has closed or when the backlog of unsent messages exceeds a threshold that makes it unwise to send more. Otherwise, the method returns true. The callback function can be used to implement flow control.
  Example: sending a server object
  The sendHandle argument can be used, for instance, to pass the handle of a TCP server object to the child process as illustrated in the example below:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const subprocess = fork('subprocess.js'); // Open up the server object and send the handle. const server = createServer(); server.on('connection', (socket) => { socket.end('handled by parent'); }); server.listen(1337, () => { subprocess.send('server', server); });
  The child would then receive the server object as:
  process.on('message', (m, server) => { if (m === 'server') { server.on('connection', (socket) => { socket.end('handled by child'); }); } });
  Once the server is now shared between the parent and child, some connections can be handled by the parent and some by the child.
  While the example above uses a server created using the node:net module, node:dgram module servers use exactly the same workflow with the exceptions of listening on a 'message' event instead of 'connection' and using server.bind() instead of server.listen(). This is, however, only supported on Unix platforms.
  Example: sending a socket object
  Similarly, the sendHandler argument can be used to pass the handle of a socket to the child process. The example below spawns two children that each handle connections with "normal" or "special" priority:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const normal = fork('subprocess.js', ['normal']); const special = fork('subprocess.js', ['special']); // Open up the server and send sockets to child. Use pauseOnConnect to prevent // the sockets from being read before they are sent to the child process. const server = createServer({ pauseOnConnect: true }); server.on('connection', (socket) => { // If this is special priority... if (socket.remoteAddress === '74.125.127.100') { special.send('socket', socket); return; } // This is normal priority. normal.send('socket', socket); }); server.listen(1337);
  The subprocess.js would receive the socket handle as the second argument passed to the event callback function:
  process.on('message', (m, socket) => { if (m === 'socket') { if (socket) { // Check that the client socket exists. // It is possible for the socket to be closed between the time it is // sent and the time it is received in the child process. socket.end(`Request handled with ${process.argv[2]} priority`); } } });
  Do not use .maxConnections on a socket that has been passed to a subprocess. The parent cannot track when the socket is destroyed.
  Any 'message' handlers in the subprocess should verify that socket exists, as the connection may have been closed during the time it takes to send the connection to the child.
  @param sendHandle
  undefined, or a net.Socket, net.Server, or dgram.Socket object.
  @param options
  The options argument, if present, is an object used to parameterize the sending of certain types of handles. options supports the following properties:
- setMaxListeners(
  n: number
  ): this;
  By default EventEmitters will print a warning if more than 10 listeners are added for a particular event. This is a useful default that helps finding memory leaks. The emitter.setMaxListeners() method allows the limit to be modified for this specific EventEmitter instance. The value can be set to Infinity (or 0) to indicate an unlimited number of listeners.
  Returns a reference to the EventEmitter, so that calls can be chained.
- unref(): void;
  By default, the parent will wait for the detached child to exit. To prevent the parent from waiting for a given subprocess to exit, use the subprocess.unref() method. Doing so will cause the parent's event loop to not include the child in its reference count, allowing the parent to exit independently of the child, unless there is an established IPC channel between the child and the parent.
  import { spawn } from 'node:child_process'; const subprocess = spawn(process.argv[0], ['child_program.js'], { detached: true, stdio: 'ignore', }); subprocess.unref();
interface ChildProcessWithoutNullStreams
Instances of the ChildProcess represent spawned child processes.
Instances of ChildProcess are not intended to be created directly. Rather, use the spawn, exec,execFile, or fork methods to create instances of ChildProcess.
- readonly channel?: null | Pipe
  The subprocess.channel property is a reference to the child's IPC channel. If no IPC channel exists, this property is undefined.
- readonly connected: boolean
  The subprocess.connected property indicates whether it is still possible to send and receive messages from a child process. When subprocess.connected is false, it is no longer possible to send or receive messages.
- readonly exitCode: null | number
  The subprocess.exitCode property indicates the exit code of the child process. If the child process is still running, the field will be null.
- readonly killed: boolean
  The subprocess.killed property indicates whether the child process successfully received a signal from subprocess.kill(). The killed property does not indicate that the child process has been terminated.
- readonly pid?: number
  Returns the process identifier (PID) of the child process. If the child process fails to spawn due to errors, then the value is undefined and error is emitted.
  import { spawn } from 'node:child_process'; const grep = spawn('grep', ['ssh']); console.log(`Spawned child pid: ${grep.pid}`); grep.stdin.end();
- readonly signalCode: null | Signals
  The subprocess.signalCode property indicates the signal received by the child process if any, else null.
- readonly spawnargs: string[]
  The subprocess.spawnargs property represents the full list of command-line arguments the child process was launched with.
- readonly spawnfile: string
  The subprocess.spawnfile property indicates the executable file name of the child process that is launched.
  For fork, its value will be equal to process.execPath. For spawn, its value will be the name of the executable file. For exec, its value will be the name of the shell in which the child process is launched.
- stderr: Readable
  A Readable Stream that represents the child process's stderr.
  If the child was spawned with stdio[2] set to anything other than 'pipe', then this will be null.
  subprocess.stderr is an alias for subprocess.stdio[2]. Both properties will refer to the same value.
  The subprocess.stderr property can be null or undefined if the child process could not be successfully spawned.
- stdin: Writable
  A Writable Stream that represents the child process's stdin.
  If a child process waits to read all of its input, the child will not continue until this stream has been closed via end().
  If the child was spawned with stdio[0] set to anything other than 'pipe', then this will be null.
  subprocess.stdin is an alias for subprocess.stdio[0]. Both properties will refer to the same value.
  The subprocess.stdin property can be null or undefined if the child process could not be successfully spawned.
- readonly stdio: [Writable, Readable, Readable, undefined | null | Writable | Readable, undefined | null | Writable | Readable]
  A sparse array of pipes to the child process, corresponding with positions in the stdio option passed to spawn that have been set to the value 'pipe'. subprocess.stdio[0], subprocess.stdio[1], and subprocess.stdio[2] are also available as subprocess.stdin, subprocess.stdout, and subprocess.stderr, respectively.
  In the following example, only the child's fd 1 (stdout) is configured as a pipe, so only the parent's subprocess.stdio[1] is a stream, all other values in the array are null.
  import assert from 'node:assert'; import fs from 'node:fs'; import child_process from 'node:child_process'; const subprocess = child_process.spawn('ls', { stdio: [ 0, // Use parent's stdin for child. 'pipe', // Pipe child's stdout to parent. fs.openSync('err.out', 'w'), // Direct child's stderr to a file. ], }); assert.strictEqual(subprocess.stdio[0], null); assert.strictEqual(subprocess.stdio[0], subprocess.stdin); assert(subprocess.stdout); assert.strictEqual(subprocess.stdio[1], subprocess.stdout); assert.strictEqual(subprocess.stdio[2], null); assert.strictEqual(subprocess.stdio[2], subprocess.stderr);
  The subprocess.stdio property can be undefined if the child process could not be successfully spawned.
- stdout: Readable
  A Readable Stream that represents the child process's stdout.
  If the child was spawned with stdio[1] set to anything other than 'pipe', then this will be null.
  subprocess.stdout is an alias for subprocess.stdio[1]. Both properties will refer to the same value.
  import { spawn } from 'node:child_process'; const subprocess = spawn('ls'); subprocess.stdout.on('data', (data) => { console.log(`Received chunk ${data}`); });
  The subprocess.stdout property can be null or undefined if the child process could not be successfully spawned.
- [events.captureRejectionSymbol]<K>(
  error: Error,
  event: string | symbol,
  ...args: AnyRest
  ): void;
- [Symbol.dispose](): void;
  Calls ChildProcess.kill with 'SIGTERM'.
- addListener(
  event: string,
  listener: (...args: any[]) => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'close',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'disconnect',
  listener: () => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'error',
  listener: (err: Error) => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'exit',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'message',
  listener: (message: Serializable, sendHandle: SendHandle) => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
  addListener(
  event: 'spawn',
  listener: () => void
  ): this;
  events.EventEmitter
  close
  disconnect
  error
  exit
  message
  spawn
- disconnect(): void;
  Closes the IPC channel between parent and child, allowing the child to exit gracefully once there are no other connections keeping it alive. After calling this method the subprocess.connected and process.connected properties in both the parent and child (respectively) will be set to false, and it will be no longer possible to pass messages between the processes.
  The 'disconnect' event will be emitted when there are no messages in the process of being received. This will most often be triggered immediately after calling subprocess.disconnect().
  When the child process is a Node.js instance (e.g. spawned using fork), the process.disconnect() method can be invoked within the child process to close the IPC channel as well.
- emit(
  event: string | symbol,
  ...args: any[]
  ): boolean;
  Synchronously calls each of the listeners registered for the event named eventName, in the order they were registered, passing the supplied arguments to each.
  Returns true if the event had listeners, false otherwise.
  import { EventEmitter } from 'node:events'; const myEmitter = new EventEmitter(); // First listener myEmitter.on('event', function firstListener() { console.log('Helloooo! first listener'); }); // Second listener myEmitter.on('event', function secondListener(arg1, arg2) { console.log(`event with parameters ${arg1}, ${arg2} in second listener`); }); // Third listener myEmitter.on('event', function thirdListener(...args) { const parameters = args.join(', '); console.log(`event with parameters ${parameters} in third listener`); }); console.log(myEmitter.listeners('event')); myEmitter.emit('event', 1, 2, 3, 4, 5); // Prints: // [ // [Function: firstListener], // [Function: secondListener], // [Function: thirdListener] // ] // Helloooo! first listener // event with parameters 1, 2 in second listener // event with parameters 1, 2, 3, 4, 5 in third listener
  emit(
  event: 'close',
  code: null | number,
  signal: null | Signals
  ): boolean;
  emit(
  event: 'disconnect'
  ): boolean;
  emit(
  event: 'error',
  err: Error
  ): boolean;
  emit(
  event: 'exit',
  code: null | number,
  signal: null | Signals
  ): boolean;
  emit(
  event: 'message',
  message: Serializable,
  sendHandle: SendHandle
  ): boolean;
  emit(
  event: 'spawn',
  listener: () => void
  ): boolean;
- eventNames(): string | symbol[];
  Returns an array listing the events for which the emitter has registered listeners. The values in the array are strings or Symbols.
  import { EventEmitter } from 'node:events'; const myEE = new EventEmitter(); myEE.on('foo', () => {}); myEE.on('bar', () => {}); const sym = Symbol('symbol'); myEE.on(sym, () => {}); console.log(myEE.eventNames()); // Prints: [ 'foo', 'bar', Symbol(symbol) ]
- getMaxListeners(): number;
  Returns the current max listener value for the EventEmitter which is either set by emitter.setMaxListeners(n) or defaults to EventEmitter.defaultMaxListeners.
- kill(
  signal?: number | Signals
  ): boolean;
  The subprocess.kill() method sends a signal to the child process. If no argument is given, the process will be sent the 'SIGTERM' signal. See signal(7) for a list of available signals. This function returns true if kill(2) succeeds, and false otherwise.
  import { spawn } from 'node:child_process'; const grep = spawn('grep', ['ssh']); grep.on('close', (code, signal) => { console.log( `child process terminated due to receipt of signal ${signal}`); }); // Send SIGHUP to process. grep.kill('SIGHUP');
  The ChildProcess object may emit an 'error' event if the signal cannot be delivered. Sending a signal to a child process that has already exited is not an error but may have unforeseen consequences. Specifically, if the process identifier (PID) has been reassigned to another process, the signal will be delivered to that process instead which can have unexpected results.
  While the function is called kill, the signal delivered to the child process may not actually terminate the process.
  See kill(2) for reference.
  On Windows, where POSIX signals do not exist, the signal argument will be ignored, and the process will be killed forcefully and abruptly (similar to 'SIGKILL'). See Signal Events for more details.
  On Linux, child processes of child processes will not be terminated when attempting to kill their parent. This is likely to happen when running a new process in a shell or with the use of the shell option of ChildProcess:
  'use strict'; import { spawn } from 'node:child_process'; const subprocess = spawn( 'sh', [ '-c', `node -e "setInterval(() => { console.log(process.pid, 'is alive') }, 500);"`, ], { stdio: ['inherit', 'inherit', 'inherit'], }, ); setTimeout(() => { subprocess.kill(); // Does not terminate the Node.js process in the shell. }, 2000);
- listenerCount<K>(
  eventName: string | symbol,
  listener?: Function
  ): number;
  Returns the number of listeners listening for the event named eventName. If listener is provided, it will return how many times the listener is found in the list of the listeners of the event.
  @param eventName
  The name of the event being listened for
  @param listener
  The event handler function
- listeners<K>(
  eventName: string | symbol
  ): Function[];
  Returns a copy of the array of listeners for the event named eventName.
  server.on('connection', (stream) => { console.log('someone connected!'); }); console.log(util.inspect(server.listeners('connection'))); // Prints: [ [Function] ]
- off<K>(
  eventName: string | symbol,
  listener: (...args: any[]) => void
  ): this;
  Alias for emitter.removeListener().
- on(
  event: string,
  listener: (...args: any[]) => void
  ): this;
  Adds the listener function to the end of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventName and listener will result in the listener being added, and called, multiple times.
  server.on('connection', (stream) => { console.log('someone connected!'); });
  Returns a reference to the EventEmitter, so that calls can be chained.
  By default, event listeners are invoked in the order they are added. The emitter.prependListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.
  import { EventEmitter } from 'node:events'; const myEE = new EventEmitter(); myEE.on('foo', () => console.log('a')); myEE.prependListener('foo', () => console.log('b')); myEE.emit('foo'); // Prints: // b // a
  @param listener
  The callback function
  on(
  event: 'close',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  on(
  event: 'disconnect',
  listener: () => void
  ): this;
  on(
  event: 'error',
  listener: (err: Error) => void
  ): this;
  on(
  event: 'exit',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  on(
  event: 'message',
  listener: (message: Serializable, sendHandle: SendHandle) => void
  ): this;
  on(
  event: 'spawn',
  listener: () => void
  ): this;
- once(
  event: string,
  listener: (...args: any[]) => void
  ): this;
  Adds a one-time listener function for the event named eventName. The next time eventName is triggered, this listener is removed and then invoked.
  server.once('connection', (stream) => { console.log('Ah, we have our first user!'); });
  Returns a reference to the EventEmitter, so that calls can be chained.
  By default, event listeners are invoked in the order they are added. The emitter.prependOnceListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.
  import { EventEmitter } from 'node:events'; const myEE = new EventEmitter(); myEE.once('foo', () => console.log('a')); myEE.prependOnceListener('foo', () => console.log('b')); myEE.emit('foo'); // Prints: // b // a
  @param listener
  The callback function
  once(
  event: 'close',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  once(
  event: 'disconnect',
  listener: () => void
  ): this;
  once(
  event: 'error',
  listener: (err: Error) => void
  ): this;
  once(
  event: 'exit',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  once(
  event: 'message',
  listener: (message: Serializable, sendHandle: SendHandle) => void
  ): this;
  once(
  event: 'spawn',
  listener: () => void
  ): this;
- prependListener(
  event: string,
  listener: (...args: any[]) => void
  ): this;
  Adds the listener function to the beginning of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventName and listener will result in the listener being added, and called, multiple times.
  server.prependListener('connection', (stream) => { console.log('someone connected!'); });
  Returns a reference to the EventEmitter, so that calls can be chained.
  @param listener
  The callback function
  prependListener(
  event: 'close',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  prependListener(
  event: 'disconnect',
  listener: () => void
  ): this;
  prependListener(
  event: 'error',
  listener: (err: Error) => void
  ): this;
  prependListener(
  event: 'exit',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  prependListener(
  event: 'message',
  listener: (message: Serializable, sendHandle: SendHandle) => void
  ): this;
  prependListener(
  event: 'spawn',
  listener: () => void
  ): this;
- prependOnceListener(
  event: string,
  listener: (...args: any[]) => void
  ): this;
  Adds a one-timelistener function for the event named eventName to the beginning of the listeners array. The next time eventName is triggered, this listener is removed, and then invoked.
  server.prependOnceListener('connection', (stream) => { console.log('Ah, we have our first user!'); });
  Returns a reference to the EventEmitter, so that calls can be chained.
  @param listener
  The callback function
  prependOnceListener(
  event: 'close',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  prependOnceListener(
  event: 'disconnect',
  listener: () => void
  ): this;
  prependOnceListener(
  event: 'error',
  listener: (err: Error) => void
  ): this;
  prependOnceListener(
  event: 'exit',
  listener: (code: null | number, signal: null | Signals) => void
  ): this;
  prependOnceListener(
  event: 'message',
  listener: (message: Serializable, sendHandle: SendHandle) => void
  ): this;
  prependOnceListener(
  event: 'spawn',
  listener: () => void
  ): this;
- rawListeners<K>(
  eventName: string | symbol
  ): Function[];
  Returns a copy of the array of listeners for the event named eventName, including any wrappers (such as those created by .once()).
  import { EventEmitter } from 'node:events'; const emitter = new EventEmitter(); emitter.once('log', () => console.log('log once')); // Returns a new Array with a function `onceWrapper` which has a property // `listener` which contains the original listener bound above const listeners = emitter.rawListeners('log'); const logFnWrapper = listeners[0]; // Logs "log once" to the console and does not unbind the `once` event logFnWrapper.listener(); // Logs "log once" to the console and removes the listener logFnWrapper(); emitter.on('log', () => console.log('log persistently')); // Will return a new Array with a single function bound by `.on()` above const newListeners = emitter.rawListeners('log'); // Logs "log persistently" twice newListeners[0](); emitter.emit('log');
- ref(): void;
  Calling subprocess.ref() after making a call to subprocess.unref() will restore the removed reference count for the child process, forcing the parent to wait for the child to exit before exiting itself.
  import { spawn } from 'node:child_process'; const subprocess = spawn(process.argv[0], ['child_program.js'], { detached: true, stdio: 'ignore', }); subprocess.unref(); subprocess.ref();
- removeAllListeners(
  eventName?: string | symbol
  ): this;
  Removes all listeners, or those of the specified eventName.
  It is bad practice to remove listeners added elsewhere in the code, particularly when the EventEmitter instance was created by some other component or module (e.g. sockets or file streams).
  Returns a reference to the EventEmitter, so that calls can be chained.
- removeListener<K>(
  eventName: string | symbol,
  listener: (...args: any[]) => void
  ): this;
  Removes the specified listener from the listener array for the event named eventName.
  const callback = (stream) => { console.log('someone connected!'); }; server.on('connection', callback); // ... server.removeListener('connection', callback);
  removeListener() will remove, at most, one instance of a listener from the listener array. If any single listener has been added multiple times to the listener array for the specified eventName, then removeListener() must be called multiple times to remove each instance.
  Once an event is emitted, all listeners attached to it at the time of emitting are called in order. This implies that any removeListener() or removeAllListeners() calls after emitting and before the last listener finishes execution will not remove them fromemit() in progress. Subsequent events behave as expected.
  import { EventEmitter } from 'node:events'; class MyEmitter extends EventEmitter {} const myEmitter = new MyEmitter(); const callbackA = () => { console.log('A'); myEmitter.removeListener('event', callbackB); }; const callbackB = () => { console.log('B'); }; myEmitter.on('event', callbackA); myEmitter.on('event', callbackB); // callbackA removes listener callbackB but it will still be called. // Internal listener array at time of emit [callbackA, callbackB] myEmitter.emit('event'); // Prints: // A // B // callbackB is now removed. // Internal listener array [callbackA] myEmitter.emit('event'); // Prints: // A
  Because listeners are managed using an internal array, calling this will change the position indices of any listener registered after the listener being removed. This will not impact the order in which listeners are called, but it means that any copies of the listener array as returned by the emitter.listeners() method will need to be recreated.
  When a single function has been added as a handler multiple times for a single event (as in the example below), removeListener() will remove the most recently added instance. In the example the once('ping') listener is removed:
  import { EventEmitter } from 'node:events'; const ee = new EventEmitter(); function pong() { console.log('pong'); } ee.on('ping', pong); ee.once('ping', pong); ee.removeListener('ping', pong); ee.emit('ping'); ee.emit('ping');
  Returns a reference to the EventEmitter, so that calls can be chained.
- send(
  message: Serializable,
  callback?: (error: null | Error) => void
  ): boolean;
  When an IPC channel has been established between the parent and child ( i.e. when using fork), the subprocess.send() method can be used to send messages to the child process. When the child process is a Node.js instance, these messages can be received via the 'message' event.
  The message goes through serialization and parsing. The resulting message might not be the same as what is originally sent.
  For example, in the parent script:
  import cp from 'node:child_process'; const n = cp.fork(`${__dirname}/sub.js`); n.on('message', (m) => { console.log('PARENT got message:', m); }); // Causes the child to print: CHILD got message: { hello: 'world' } n.send({ hello: 'world' });
  And then the child script, 'sub.js' might look like this:
  process.on('message', (m) => { console.log('CHILD got message:', m); }); // Causes the parent to print: PARENT got message: { foo: 'bar', baz: null } process.send({ foo: 'bar', baz: NaN });
  Child Node.js processes will have a process.send() method of their own that allows the child to send messages back to the parent.
  There is a special case when sending a {cmd: 'NODE_foo'} message. Messages containing a NODE_ prefix in the cmd property are reserved for use within Node.js core and will not be emitted in the child's 'message' event. Rather, such messages are emitted using the 'internalMessage' event and are consumed internally by Node.js. Applications should avoid using such messages or listening for 'internalMessage' events as it is subject to change without notice.
  The optional sendHandle argument that may be passed to subprocess.send() is for passing a TCP server or socket object to the child process. The child will receive the object as the second argument passed to the callback function registered on the 'message' event. Any data that is received and buffered in the socket will not be sent to the child. Sending IPC sockets is not supported on Windows.
  The optional callback is a function that is invoked after the message is sent but before the child may have received it. The function is called with a single argument: null on success, or an Error object on failure.
  If no callback function is provided and the message cannot be sent, an 'error' event will be emitted by the ChildProcess object. This can happen, for instance, when the child process has already exited.
  subprocess.send() will return false if the channel has closed or when the backlog of unsent messages exceeds a threshold that makes it unwise to send more. Otherwise, the method returns true. The callback function can be used to implement flow control.
  Example: sending a server object
  The sendHandle argument can be used, for instance, to pass the handle of a TCP server object to the child process as illustrated in the example below:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const subprocess = fork('subprocess.js'); // Open up the server object and send the handle. const server = createServer(); server.on('connection', (socket) => { socket.end('handled by parent'); }); server.listen(1337, () => { subprocess.send('server', server); });
  The child would then receive the server object as:
  process.on('message', (m, server) => { if (m === 'server') { server.on('connection', (socket) => { socket.end('handled by child'); }); } });
  Once the server is now shared between the parent and child, some connections can be handled by the parent and some by the child.
  While the example above uses a server created using the node:net module, node:dgram module servers use exactly the same workflow with the exceptions of listening on a 'message' event instead of 'connection' and using server.bind() instead of server.listen(). This is, however, only supported on Unix platforms.
  Example: sending a socket object
  Similarly, the sendHandler argument can be used to pass the handle of a socket to the child process. The example below spawns two children that each handle connections with "normal" or "special" priority:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const normal = fork('subprocess.js', ['normal']); const special = fork('subprocess.js', ['special']); // Open up the server and send sockets to child. Use pauseOnConnect to prevent // the sockets from being read before they are sent to the child process. const server = createServer({ pauseOnConnect: true }); server.on('connection', (socket) => { // If this is special priority... if (socket.remoteAddress === '74.125.127.100') { special.send('socket', socket); return; } // This is normal priority. normal.send('socket', socket); }); server.listen(1337);
  The subprocess.js would receive the socket handle as the second argument passed to the event callback function:
  process.on('message', (m, socket) => { if (m === 'socket') { if (socket) { // Check that the client socket exists. // It is possible for the socket to be closed between the time it is // sent and the time it is received in the child process. socket.end(`Request handled with ${process.argv[2]} priority`); } } });
  Do not use .maxConnections on a socket that has been passed to a subprocess. The parent cannot track when the socket is destroyed.
  Any 'message' handlers in the subprocess should verify that socket exists, as the connection may have been closed during the time it takes to send the connection to the child.
  send(
  message: Serializable,
  sendHandle?: SendHandle,
  callback?: (error: null | Error) => void
  ): boolean;
  When an IPC channel has been established between the parent and child ( i.e. when using fork), the subprocess.send() method can be used to send messages to the child process. When the child process is a Node.js instance, these messages can be received via the 'message' event.
  The message goes through serialization and parsing. The resulting message might not be the same as what is originally sent.
  For example, in the parent script:
  import cp from 'node:child_process'; const n = cp.fork(`${__dirname}/sub.js`); n.on('message', (m) => { console.log('PARENT got message:', m); }); // Causes the child to print: CHILD got message: { hello: 'world' } n.send({ hello: 'world' });
  And then the child script, 'sub.js' might look like this:
  process.on('message', (m) => { console.log('CHILD got message:', m); }); // Causes the parent to print: PARENT got message: { foo: 'bar', baz: null } process.send({ foo: 'bar', baz: NaN });
  Child Node.js processes will have a process.send() method of their own that allows the child to send messages back to the parent.
  There is a special case when sending a {cmd: 'NODE_foo'} message. Messages containing a NODE_ prefix in the cmd property are reserved for use within Node.js core and will not be emitted in the child's 'message' event. Rather, such messages are emitted using the 'internalMessage' event and are consumed internally by Node.js. Applications should avoid using such messages or listening for 'internalMessage' events as it is subject to change without notice.
  The optional sendHandle argument that may be passed to subprocess.send() is for passing a TCP server or socket object to the child process. The child will receive the object as the second argument passed to the callback function registered on the 'message' event. Any data that is received and buffered in the socket will not be sent to the child. Sending IPC sockets is not supported on Windows.
  The optional callback is a function that is invoked after the message is sent but before the child may have received it. The function is called with a single argument: null on success, or an Error object on failure.
  If no callback function is provided and the message cannot be sent, an 'error' event will be emitted by the ChildProcess object. This can happen, for instance, when the child process has already exited.
  subprocess.send() will return false if the channel has closed or when the backlog of unsent messages exceeds a threshold that makes it unwise to send more. Otherwise, the method returns true. The callback function can be used to implement flow control.
  Example: sending a server object
  The sendHandle argument can be used, for instance, to pass the handle of a TCP server object to the child process as illustrated in the example below:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const subprocess = fork('subprocess.js'); // Open up the server object and send the handle. const server = createServer(); server.on('connection', (socket) => { socket.end('handled by parent'); }); server.listen(1337, () => { subprocess.send('server', server); });
  The child would then receive the server object as:
  process.on('message', (m, server) => { if (m === 'server') { server.on('connection', (socket) => { socket.end('handled by child'); }); } });
  Once the server is now shared between the parent and child, some connections can be handled by the parent and some by the child.
  While the example above uses a server created using the node:net module, node:dgram module servers use exactly the same workflow with the exceptions of listening on a 'message' event instead of 'connection' and using server.bind() instead of server.listen(). This is, however, only supported on Unix platforms.
  Example: sending a socket object
  Similarly, the sendHandler argument can be used to pass the handle of a socket to the child process. The example below spawns two children that each handle connections with "normal" or "special" priority:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const normal = fork('subprocess.js', ['normal']); const special = fork('subprocess.js', ['special']); // Open up the server and send sockets to child. Use pauseOnConnect to prevent // the sockets from being read before they are sent to the child process. const server = createServer({ pauseOnConnect: true }); server.on('connection', (socket) => { // If this is special priority... if (socket.remoteAddress === '74.125.127.100') { special.send('socket', socket); return; } // This is normal priority. normal.send('socket', socket); }); server.listen(1337);
  The subprocess.js would receive the socket handle as the second argument passed to the event callback function:
  process.on('message', (m, socket) => { if (m === 'socket') { if (socket) { // Check that the client socket exists. // It is possible for the socket to be closed between the time it is // sent and the time it is received in the child process. socket.end(`Request handled with ${process.argv[2]} priority`); } } });
  Do not use .maxConnections on a socket that has been passed to a subprocess. The parent cannot track when the socket is destroyed.
  Any 'message' handlers in the subprocess should verify that socket exists, as the connection may have been closed during the time it takes to send the connection to the child.
  @param sendHandle
  undefined, or a net.Socket, net.Server, or dgram.Socket object.
  send(
  message: Serializable,
  sendHandle?: SendHandle,
  options?: MessageOptions,
  callback?: (error: null | Error) => void
  ): boolean;
  When an IPC channel has been established between the parent and child ( i.e. when using fork), the subprocess.send() method can be used to send messages to the child process. When the child process is a Node.js instance, these messages can be received via the 'message' event.
  The message goes through serialization and parsing. The resulting message might not be the same as what is originally sent.
  For example, in the parent script:
  import cp from 'node:child_process'; const n = cp.fork(`${__dirname}/sub.js`); n.on('message', (m) => { console.log('PARENT got message:', m); }); // Causes the child to print: CHILD got message: { hello: 'world' } n.send({ hello: 'world' });
  And then the child script, 'sub.js' might look like this:
  process.on('message', (m) => { console.log('CHILD got message:', m); }); // Causes the parent to print: PARENT got message: { foo: 'bar', baz: null } process.send({ foo: 'bar', baz: NaN });
  Child Node.js processes will have a process.send() method of their own that allows the child to send messages back to the parent.
  There is a special case when sending a {cmd: 'NODE_foo'} message. Messages containing a NODE_ prefix in the cmd property are reserved for use within Node.js core and will not be emitted in the child's 'message' event. Rather, such messages are emitted using the 'internalMessage' event and are consumed internally by Node.js. Applications should avoid using such messages or listening for 'internalMessage' events as it is subject to change without notice.
  The optional sendHandle argument that may be passed to subprocess.send() is for passing a TCP server or socket object to the child process. The child will receive the object as the second argument passed to the callback function registered on the 'message' event. Any data that is received and buffered in the socket will not be sent to the child. Sending IPC sockets is not supported on Windows.
  The optional callback is a function that is invoked after the message is sent but before the child may have received it. The function is called with a single argument: null on success, or an Error object on failure.
  If no callback function is provided and the message cannot be sent, an 'error' event will be emitted by the ChildProcess object. This can happen, for instance, when the child process has already exited.
  subprocess.send() will return false if the channel has closed or when the backlog of unsent messages exceeds a threshold that makes it unwise to send more. Otherwise, the method returns true. The callback function can be used to implement flow control.
  Example: sending a server object
  The sendHandle argument can be used, for instance, to pass the handle of a TCP server object to the child process as illustrated in the example below:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const subprocess = fork('subprocess.js'); // Open up the server object and send the handle. const server = createServer(); server.on('connection', (socket) => { socket.end('handled by parent'); }); server.listen(1337, () => { subprocess.send('server', server); });
  The child would then receive the server object as:
  process.on('message', (m, server) => { if (m === 'server') { server.on('connection', (socket) => { socket.end('handled by child'); }); } });
  Once the server is now shared between the parent and child, some connections can be handled by the parent and some by the child.
  While the example above uses a server created using the node:net module, node:dgram module servers use exactly the same workflow with the exceptions of listening on a 'message' event instead of 'connection' and using server.bind() instead of server.listen(). This is, however, only supported on Unix platforms.
  Example: sending a socket object
  Similarly, the sendHandler argument can be used to pass the handle of a socket to the child process. The example below spawns two children that each handle connections with "normal" or "special" priority:
  import { createServer } from 'node:net'; import { fork } from 'node:child_process'; const normal = fork('subprocess.js', ['normal']); const special = fork('subprocess.js', ['special']); // Open up the server and send sockets to child. Use pauseOnConnect to prevent // the sockets from being read before they are sent to the child process. const server = createServer({ pauseOnConnect: true }); server.on('connection', (socket) => { // If this is special priority... if (socket.remoteAddress === '74.125.127.100') { special.send('socket', socket); return; } // This is normal priority. normal.send('socket', socket); }); server.listen(1337);
  The subprocess.js would receive the socket handle as the second argument passed to the event callback function:
  process.on('message', (m, socket) => { if (m === 'socket') { if (socket) { // Check that the client socket exists. // It is possible for the socket to be closed between the time it is // sent and the time it is received in the child process. socket.end(`Request handled with ${process.argv[2]} priority`); } } });
  Do not use .maxConnections on a socket that has been passed to a subprocess. The parent cannot track when the socket is destroyed.
  Any 'message' handlers in the subprocess should verify that socket exists, as the connection may have been closed during the time it takes to send the connection to the child.
  @param sendHandle
  undefined, or a net.Socket, net.Server, or dgram.Socket object.
  @param options
  The options argument, if present, is an object used to parameterize the sending of certain types of handles. options supports the following properties:
- setMaxListeners(
  n: number
  ): this;
  By default EventEmitters will print a warning if more than 10 listeners are added for a particular event. This is a useful default that helps finding memory leaks. The emitter.setMaxListeners() method allows the limit to be modified for this specific EventEmitter instance. The value can be set to Infinity (or 0) to indicate an unlimited number of listeners.
  Returns a reference to the EventEmitter, so that calls can be chained.
- unref(): void;
  By default, the parent will wait for the detached child to exit. To prevent the parent from waiting for a given subprocess to exit, use the subprocess.unref() method. Doing so will cause the parent's event loop to not include the child in its reference count, allowing the parent to exit independently of the child, unless there is an established IPC channel between the child and the parent.
  import { spawn } from 'node:child_process'; const subprocess = spawn(process.argv[0], ['child_program.js'], { detached: true, stdio: 'ignore', }); subprocess.unref();
interface CommonExecOptions
- cwd?: string | URL
- encoding?: null | 'buffer' | BufferEncoding
- env?: ProcessEnv
- gid?: number
- input?: string | ArrayBufferView<ArrayBufferLike>
- killSignal?: number | Signals
- maxBuffer?: number
- stdio?: StdioOptions
  Can be set to 'pipe', 'inherit, or 'ignore', or an array of these strings. If passed as an array, the first element is used for stdin, the second for stdout, and the third for stderr. A fourth element can be used to specify the stdio behavior beyond the standard streams. See ChildProcess.stdio for more information.
- timeout?: number
- uid?: number
- windowsHide?: boolean
interface CommonOptions
- cwd?: string | URL
- env?: ProcessEnv
- gid?: number
- timeout?: number
- uid?: number
- windowsHide?: boolean
interface CommonSpawnOptions
- argv0?: string
- cwd?: string | URL
- env?: ProcessEnv
- gid?: number
- killSignal?: number | Signals
  The signal value to be used when the spawned process will be killed by the abort signal.
- serialization?: SerializationType
  Specify the kind of serialization used for sending messages between processes.
- shell?: string | boolean
- signal?: AbortSignal
  When provided the corresponding AbortController can be used to cancel an asynchronous action.
- stdio?: StdioOptions
  Can be set to 'pipe', 'inherit', 'overlapped', or 'ignore', or an array of these strings. If passed as an array, the first element is used for stdin, the second for stdout, and the third for stderr. A fourth element can be used to specify the stdio behavior beyond the standard streams. See ChildProcess.stdio for more information.
- timeout?: number
- uid?: number
- windowsHide?: boolean
- windowsVerbatimArguments?: boolean
interface ExecException
- cause?: unknown
  The cause of the error.
- cmd?: string
- code?: number
- killed?: boolean
- message: string
- name: string
- signal?: Signals
- stack?: string
- stderr?: string
- stdout?: string
interface ExecFileOptions
- cwd?: string | URL
- env?: ProcessEnv
- gid?: number
- killSignal?: number | Signals
- maxBuffer?: number
- shell?: string | boolean
- signal?: AbortSignal
  When provided the corresponding AbortController can be used to cancel an asynchronous action.
- timeout?: number
- uid?: number
- windowsHide?: boolean
- windowsVerbatimArguments?: boolean
interface ExecFileOptionsWithBufferEncoding
- cwd?: string | URL
- encoding: null | 'buffer'
- env?: ProcessEnv
- gid?: number
- killSignal?: number | Signals
- maxBuffer?: number
- shell?: string | boolean
- signal?: AbortSignal
  When provided the corresponding AbortController can be used to cancel an asynchronous action.
- timeout?: number
- uid?: number
- windowsHide?: boolean
- windowsVerbatimArguments?: boolean
interface ExecFileOptionsWithOtherEncoding
- cwd?: string | URL
- encoding: BufferEncoding
- env?: ProcessEnv
- gid?: number
- killSignal?: number | Signals
- maxBuffer?: number
- shell?: string | boolean
- signal?: AbortSignal
  When provided the corresponding AbortController can be used to cancel an asynchronous action.
- timeout?: number
- uid?: number
- windowsHide?: boolean
- windowsVerbatimArguments?: boolean
interface ExecFileOptionsWithStringEncoding
- cwd?: string | URL
- encoding: BufferEncoding
- env?: ProcessEnv
- gid?: number
- killSignal?: number | Signals
- maxBuffer?: number
- shell?: string | boolean
- signal?: AbortSignal
  When provided the corresponding AbortController can be used to cancel an asynchronous action.
- timeout?: number
- uid?: number
- windowsHide?: boolean
- windowsVerbatimArguments?: boolean
interface ExecFileSyncOptions
- cwd?: string | URL
- encoding?: null | 'buffer' | BufferEncoding
- env?: ProcessEnv
- gid?: number
- input?: string | ArrayBufferView<ArrayBufferLike>
- killSignal?: number | Signals
- maxBuffer?: number
- shell?: string | boolean
- stdio?: StdioOptions
  Can be set to 'pipe', 'inherit, or 'ignore', or an array of these strings. If passed as an array, the first element is used for stdin, the second for stdout, and the third for stderr. A fourth element can be used to specify the stdio behavior beyond the standard streams. See ChildProcess.stdio for more information.
- timeout?: number
- uid?: number
- windowsHide?: boolean
interface ExecFileSyncOptionsWithBufferEncoding
- cwd?: string | URL
- encoding?: null | 'buffer'
- env?: ProcessEnv
- gid?: number
- input?: string | ArrayBufferView<ArrayBufferLike>
- killSignal?: number | Signals
- maxBuffer?: number
- shell?: string | boolean
- stdio?: StdioOptions
  Can be set to 'pipe', 'inherit, or 'ignore', or an array of these strings. If passed as an array, the first element is used for stdin, the second for stdout, and the third for stderr. A fourth element can be used to specify the stdio behavior beyond the standard streams. See ChildProcess.stdio for more information.
- timeout?: number
- uid?: number
- windowsHide?: boolean
interface ExecFileSyncOptionsWithStringEncoding
- cwd?: string | URL
- encoding: BufferEncoding
- env?: ProcessEnv
- gid?: number
- input?: string | ArrayBufferView<ArrayBufferLike>
- killSignal?: number | Signals
- maxBuffer?: number
- shell?: string | boolean
- stdio?: StdioOptions
  Can be set to 'pipe', 'inherit, or 'ignore', or an array of these strings. If passed as an array, the first element is used for stdin, the second for stdout, and the third for stderr. A fourth element can be used to specify the stdio behavior beyond the standard streams. See ChildProcess.stdio for more information.
- timeout?: number
- uid?: number
- windowsHide?: boolean
interface ExecOptions
- cwd?: string | URL
- env?: ProcessEnv
- gid?: number
- killSignal?: number | Signals
- maxBuffer?: number
- shell?: string
- signal?: AbortSignal
- timeout?: number
- uid?: number
- windowsHide?: boolean
interface ExecOptionsWithBufferEncoding
- cwd?: string | URL
- encoding: null | BufferEncoding
- env?: ProcessEnv
- gid?: number
- killSignal?: number | Signals
- maxBuffer?: number
- shell?: string
- signal?: AbortSignal
- timeout?: number
- uid?: number
- windowsHide?: boolean
interface ExecOptionsWithStringEncoding
- cwd?: string | URL
- encoding: BufferEncoding
- env?: ProcessEnv
- gid?: number
- killSignal?: number | Signals
- maxBuffer?: number
- shell?: string
- signal?: AbortSignal
- timeout?: number
- uid?: number
- windowsHide?: boolean
interface ExecSyncOptions
- cwd?: string | URL
- encoding?: null | 'buffer' | BufferEncoding
- env?: ProcessEnv
- gid?: number
- input?: string | ArrayBufferView<ArrayBufferLike>
- killSignal?: number | Signals
- maxBuffer?: number
- shell?: string
- stdio?: StdioOptions
  Can be set to 'pipe', 'inherit, or 'ignore', or an array of these strings. If passed as an array, the first element is used for stdin, the second for stdout, and the third for stderr. A fourth element can be used to specify the stdio behavior beyond the standard streams. See ChildProcess.stdio for more information.
- timeout?: number
- uid?: number
- windowsHide?: boolean
interface ExecSyncOptionsWithBufferEncoding
- cwd?: string | URL
- encoding?: null | 'buffer'
- env?: ProcessEnv
- gid?: number
- input?: string | ArrayBufferView<ArrayBufferLike>
- killSignal?: number | Signals
- maxBuffer?: number
- shell?: string
- stdio?: StdioOptions
  Can be set to 'pipe', 'inherit, or 'ignore', or an array of these strings. If passed as an array, the first element is used for stdin, the second for stdout, and the third for stderr. A fourth element can be used to specify the stdio behavior beyond the standard streams. See ChildProcess.stdio for more information.
- timeout?: number
- uid?: number
- windowsHide?: boolean
interface ExecSyncOptionsWithStringEncoding
- cwd?: string | URL
- encoding: BufferEncoding
- env?: ProcessEnv
- gid?: number
- input?: string | ArrayBufferView<ArrayBufferLike>
- killSignal?: number | Signals
- maxBuffer?: number
- shell?: string
- stdio?: StdioOptions
  Can be set to 'pipe', 'inherit, or 'ignore', or an array of these strings. If passed as an array, the first element is used for stdin, the second for stdout, and the third for stderr. A fourth element can be used to specify the stdio behavior beyond the standard streams. See ChildProcess.stdio for more information.
- timeout?: number
- uid?: number
- windowsHide?: boolean
interface ForkOptions
- cwd?: string | URL
- detached?: boolean
- env?: ProcessEnv
- execArgv?: string[]
- execPath?: string
- gid?: number
- killSignal?: number | Signals
  The signal value to be used when the spawned process will be killed by the abort signal.
- serialization?: SerializationType
  Specify the kind of serialization used for sending messages between processes.
- signal?: AbortSignal
  When provided the corresponding AbortController can be used to cancel an asynchronous action.
- silent?: boolean
- stdio?: StdioOptions
  Can be set to 'pipe', 'inherit', 'overlapped', or 'ignore', or an array of these strings. If passed as an array, the first element is used for stdin, the second for stdout, and the third for stderr. A fourth element can be used to specify the stdio behavior beyond the standard streams. See ChildProcess.stdio for more information.
- timeout?: number
  In milliseconds the maximum amount of time the process is allowed to run.
- uid?: number
- windowsVerbatimArguments?: boolean
interface MessageOptions
- keepOpen?: boolean
interface MessagingOptions
- killSignal?: number | Signals
  The signal value to be used when the spawned process will be killed by the abort signal.
- serialization?: SerializationType
  Specify the kind of serialization used for sending messages between processes.
- signal?: AbortSignal
  When provided the corresponding AbortController can be used to cancel an asynchronous action.
- timeout?: number
  In milliseconds the maximum amount of time the process is allowed to run.
interface ProcessEnvOptions
- cwd?: string | URL
- env?: ProcessEnv
- gid?: number
- uid?: number
interface PromiseWithChild<T>
- readonly [Symbol.toStringTag]: string
- child: ChildProcess
- catch<TResult = never>(
  onrejected?: null | (reason: any) => TResult | PromiseLike<TResult>
  ): Promise<T | TResult>;
  Attaches a callback for only the rejection of the Promise.
  @param onrejected
  The callback to execute when the Promise is rejected.
  @returns
  A Promise for the completion of the callback.
- finally(
  onfinally?: null | () => void
  ): Promise<T>;
  Attaches a callback that is invoked when the Promise is settled (fulfilled or rejected). The resolved value cannot be modified from the callback.
  @param onfinally
  The callback to execute when the Promise is settled (fulfilled or rejected).
  @returns
  A Promise for the completion of the callback.
- then<TResult1 = T, TResult2 = never>(
  onfulfilled?: null | (value: T) => TResult1 | PromiseLike<TResult1>,
  onrejected?: null | (reason: any) => TResult2 | PromiseLike<TResult2>
  ): Promise<TResult1 | TResult2>;
  Attaches callbacks for the resolution and/or rejection of the Promise.
  @param onfulfilled
  The callback to execute when the Promise is resolved.
  @param onrejected
  The callback to execute when the Promise is rejected.
  @returns
  A Promise for the completion of which ever callback is executed.
interface SpawnOptions
- argv0?: string
- cwd?: string | URL
- detached?: boolean
- env?: ProcessEnv
- gid?: number
- killSignal?: number | Signals
  The signal value to be used when the spawned process will be killed by the abort signal.
- serialization?: SerializationType
  Specify the kind of serialization used for sending messages between processes.
- shell?: string | boolean
- signal?: AbortSignal
  When provided the corresponding AbortController can be used to cancel an asynchronous action.
- stdio?: StdioOptions
  Can be set to 'pipe', 'inherit', 'overlapped', or 'ignore', or an array of these strings. If passed as an array, the first element is used for stdin, the second for stdout, and the third for stderr. A fourth element can be used to specify the stdio behavior beyond the standard streams. See ChildProcess.stdio for more information.
- timeout?: number
- uid?: number
- windowsHide?: boolean
- windowsVerbatimArguments?: boolean
interface SpawnOptionsWithoutStdio
- argv0?: string
- cwd?: string | URL
- detached?: boolean
- env?: ProcessEnv
- gid?: number
- killSignal?: number | Signals
  The signal value to be used when the spawned process will be killed by the abort signal.
- serialization?: SerializationType
  Specify the kind of serialization used for sending messages between processes.
- shell?: string | boolean
- signal?: AbortSignal
  When provided the corresponding AbortController can be used to cancel an asynchronous action.
- stdio?: StdioPipeNamed | StdioPipe[]
  Can be set to 'pipe', 'inherit', 'overlapped', or 'ignore', or an array of these strings. If passed as an array, the first element is used for stdin, the second for stdout, and the third for stderr. A fourth element can be used to specify the stdio behavior beyond the standard streams. See ChildProcess.stdio for more information.
- timeout?: number
- uid?: number
- windowsHide?: boolean
- windowsVerbatimArguments?: boolean
interface SpawnOptionsWithStdioTuple<Stdin extends StdioNull | StdioPipe, Stdout extends StdioNull | StdioPipe, Stderr extends StdioNull | StdioPipe>
- argv0?: string
- cwd?: string | URL
- detached?: boolean
- env?: ProcessEnv
- gid?: number
- killSignal?: number | Signals
  The signal value to be used when the spawned process will be killed by the abort signal.
- serialization?: SerializationType
  Specify the kind of serialization used for sending messages between processes.
- shell?: string | boolean
- signal?: AbortSignal
  When provided the corresponding AbortController can be used to cancel an asynchronous action.
- stdio: [Stdin, Stdout, Stderr]
  Can be set to 'pipe', 'inherit', 'overlapped', or 'ignore', or an array of these strings. If passed as an array, the first element is used for stdin, the second for stdout, and the third for stderr. A fourth element can be used to specify the stdio behavior beyond the standard streams. See ChildProcess.stdio for more information.
- timeout?: number
- uid?: number
- windowsHide?: boolean
- windowsVerbatimArguments?: boolean
interface SpawnSyncOptions
- argv0?: string
- cwd?: string | URL
- encoding?: null | 'buffer' | BufferEncoding
- env?: ProcessEnv
- gid?: number
- input?: string | ArrayBufferView<ArrayBufferLike>
- killSignal?: number | Signals
  The signal value to be used when the spawned process will be killed by the abort signal.
- maxBuffer?: number
- serialization?: SerializationType
  Specify the kind of serialization used for sending messages between processes.
- shell?: string | boolean
- signal?: AbortSignal
  When provided the corresponding AbortController can be used to cancel an asynchronous action.
- stdio?: StdioOptions
  Can be set to 'pipe', 'inherit', 'overlapped', or 'ignore', or an array of these strings. If passed as an array, the first element is used for stdin, the second for stdout, and the third for stderr. A fourth element can be used to specify the stdio behavior beyond the standard streams. See ChildProcess.stdio for more information.
- timeout?: number
- uid?: number
- windowsHide?: boolean
- windowsVerbatimArguments?: boolean
interface SpawnSyncOptionsWithBufferEncoding
- argv0?: string
- cwd?: string | URL
- encoding?: null | 'buffer'
- env?: ProcessEnv
- gid?: number
- input?: string | ArrayBufferView<ArrayBufferLike>
- killSignal?: number | Signals
  The signal value to be used when the spawned process will be killed by the abort signal.
- maxBuffer?: number
- serialization?: SerializationType
  Specify the kind of serialization used for sending messages between processes.
- shell?: string | boolean
- signal?: AbortSignal
  When provided the corresponding AbortController can be used to cancel an asynchronous action.
- stdio?: StdioOptions
  Can be set to 'pipe', 'inherit', 'overlapped', or 'ignore', or an array of these strings. If passed as an array, the first element is used for stdin, the second for stdout, and the third for stderr. A fourth element can be used to specify the stdio behavior beyond the standard streams. See ChildProcess.stdio for more information.
- timeout?: number
- uid?: number
- windowsHide?: boolean
- windowsVerbatimArguments?: boolean
interface SpawnSyncOptionsWithStringEncoding
- argv0?: string
- cwd?: string | URL
- encoding: BufferEncoding
- env?: ProcessEnv
- gid?: number
- input?: string | ArrayBufferView<ArrayBufferLike>
- killSignal?: number | Signals
  The signal value to be used when the spawned process will be killed by the abort signal.
- maxBuffer?: number
- serialization?: SerializationType
  Specify the kind of serialization used for sending messages between processes.
- shell?: string | boolean
- signal?: AbortSignal
  When provided the corresponding AbortController can be used to cancel an asynchronous action.
- stdio?: StdioOptions
  Can be set to 'pipe', 'inherit', 'overlapped', or 'ignore', or an array of these strings. If passed as an array, the first element is used for stdin, the second for stdout, and the third for stderr. A fourth element can be used to specify the stdio behavior beyond the standard streams. See ChildProcess.stdio for more information.
- timeout?: number
- uid?: number
- windowsHide?: boolean
- windowsVerbatimArguments?: boolean
interface SpawnSyncReturns<T>
- error?: Error
- output: null | T[]
- pid: number
- signal: null | Signals
- status: null | number
- stderr: T
- stdout: T
type ExecFileException = Omit<ExecException, 'code'> & Omit<NodeJS.ErrnoException, 'code'> & { code: string | number | null }
type IOType = 'overlapped' | 'pipe' | 'ignore' | 'inherit'
type SendHandle = net.Socket | net.Server | dgram.Socket | undefined
type Serializable = string | object | number | boolean | bigint
type SerializationType = 'json' | 'advanced'
type StdioNull = 'inherit' | 'ignore' | Stream
type StdioOptions = IOType | IOType | 'ipc' | Stream | number | null | undefined[]
type StdioPipe = undefined | null | StdioPipeNamed
type StdioPipeNamed = 'pipe' | 'overlapped'

child_process

class ChildProcess

Example: sending a server object

Example: sending a socket object

Example: sending a server object

Example: sending a socket object

Example: sending a server object

Example: sending a socket object

Type definitions

namespace exec

namespace execFile

interface ChildProcessByStdio<I extends null | Writable, O extends null | Readable, E extends null | Readable>

Example: sending a server object

Example: sending a socket object

Example: sending a server object

Example: sending a socket object

Example: sending a server object

Example: sending a socket object

interface ChildProcessWithoutNullStreams

Example: sending a server object

Example: sending a socket object

Example: sending a server object

Example: sending a socket object

Example: sending a server object

Example: sending a socket object

interface CommonExecOptions

interface CommonOptions

interface CommonSpawnOptions

interface ExecException

interface ExecFileOptions

interface ExecFileOptionsWithBufferEncoding

interface ExecFileOptionsWithOtherEncoding

interface ExecFileOptionsWithStringEncoding

interface ExecFileSyncOptions

interface ExecFileSyncOptionsWithBufferEncoding

interface ExecFileSyncOptionsWithStringEncoding

interface ExecOptions

interface ExecOptionsWithBufferEncoding

interface ExecOptionsWithStringEncoding

interface ExecSyncOptions

interface ExecSyncOptionsWithBufferEncoding

interface ExecSyncOptionsWithStringEncoding

interface ForkOptions

interface MessageOptions

interface MessagingOptions

interface ProcessEnvOptions

interface PromiseWithChild<T>

interface SpawnOptions

interface SpawnOptionsWithoutStdio

interface SpawnOptionsWithStdioTuple<Stdin extends StdioNull | StdioPipe, Stdout extends StdioNull | StdioPipe, Stderr extends StdioNull | StdioPipe>

interface SpawnSyncOptions

interface SpawnSyncOptionsWithBufferEncoding

interface SpawnSyncOptionsWithStringEncoding

interface SpawnSyncReturns<T>