Symbol

SpawnOptions.OptionsObject.ipc

ipc(message: any, subprocess: Subprocess<In, Out, Err>): void

When specified, Bun will open an IPC channel to the subprocess. The passed callback is called for incoming messages, and subprocess.send can send messages to the subprocess. Messages are serialized using the JSC serialize API, which allows for the same types that postMessage/structuredClone supports.

The subprocess can send and recieve messages by using process.send and process.on("message"), respectively. This is the same API as what Node.js exposes when child_process.fork() is used.

Currently, this is only compatible with processes that are other bun instances.

@param subprocess

The Subprocess that sent the message

Referenced types

interface Subprocess<In extends SpawnOptions.Writable = SpawnOptions.Writable, Out extends SpawnOptions.Readable = SpawnOptions.Readable, Err extends SpawnOptions.Readable = SpawnOptions.Readable>

A process created by Bun.spawn.

This type accepts 3 optional type parameters which correspond to the stdio array from the options object. Instead of specifying these, you should use one of the following utility types instead:

ReadableSubprocess (any, pipe, pipe)
WritableSubprocess (pipe, any, any)
PipedSubprocess (pipe, pipe, pipe)
NullSubprocess (ignore, ignore, ignore)

readonly exitCode: null | number
Synchronously get the exit code of the process
If the process hasn't exited yet, this will return null
readonly exited: Promise<number>
The exit code of the process
The promise will resolve when the process exits
readonly killed: boolean
Has the process exited?
readonly pid: number
The process ID of the child process
const { pid } = Bun.spawn({ cmd: ["echo", "hello"] }); console.log(pid); // 1234
readonly readable: ReadableToIO<Out>
This returns the same value as Subprocess.stdout
It exists for compatibility with ReadableStream.pipeThrough
readonly signalCode: null | Signals
Synchronously get the signal code of the process
If the process never sent a signal code, this will return null
To receive signal code changes, use the onExit callback.
If the signal code is unknown, it will return the original signal code number, but that case should essentially never happen.
readonly stderr: ReadableToIO<Err>
readonly stdin: WritableToIO<In>
readonly stdout: ReadableToIO<Out>
[Symbol.asyncDispose](): PromiseLike<void>
disconnect(): void
Disconnect the IPC channel to the subprocess. This is only supported if the subprocess was created with the ipc option.
kill(exitCode?: number | Signals): void
Kill the process
@param exitCode
The exitCode to send to the process
ref(): void
This method will tell Bun to wait for this process to exit after you already called unref().
Before shutting down, Bun will wait for all subprocesses to exit by default
resourceUsage(): undefined | ResourceUsage
Get the resource usage information of the process (max RSS, CPU time, etc)
Only available after the process has exited
If the process hasn't exited yet, this will return undefined
send(message: any): void
Send a message to the subprocess. This is only supported if the subprocess was created with the ipc option, and is another instance of bun.
Messages are serialized using the JSC serialize API, which allows for the same types that postMessage/structuredClone supports.
unref(): void
Before shutting down, Bun will wait for all subprocesses to exit by default
This method will tell Bun to not wait for this process to exit before shutting down.