When using Bun.spawn(), the child process inherits the stderr of the spawning process. If instead you'd prefer to read and handle stderr, set the stderr option to "pipe".
const proc = Bun.spawn(["echo", "hello"], {
stderr: "pipe",
});
proc.stderr; // => ReadableStream
To read stderr until the child process exits, use the Bun.readableStreamToText() convenience function.
const proc = Bun.spawn(["echo", "hello"], {
stderr: "pipe",
});
const errors: string = await Bun.readableStreamToText(proc.stderr);
if (errors) {
// handle errors
}
See Docs > API > Child processes for complete documentation.