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Use Bun.spawn() to spawn a child process. When spawning a second bun process, you can open a direct inter-process communication (IPC) channel between the two processes.
This API is only compatible with other bun processes. Use process.execPath to get a path to the currently running bun executable.
/icons/typescript.svgparent.ts
const child = Bun.spawn(['bun', 'child.ts'], {
	ipc(message) {
		/**
		 * The message received from the sub process
		 **/
	},
});
The parent process can send messages to the subprocess using the .send() method on the returned Subprocess instance. A reference to the sending subprocess is also available as the second argument in the ipc handler.
/icons/typescript.svgparent.ts
const childProc = Bun.spawn(['bun', 'child.ts'], {
	ipc(message, childProc) {
		/**
		 * The message received from the sub process
		 **/
		childProc.send('Respond to child');
	},
});

childProc.send('I am your father'); // The parent can send messages to the child as well
Meanwhile the child process can send messages to its parent using with process.send() and receive messages with process.on("message"). This is the same API used for child_process.fork() in Node.js.
/icons/typescript.svgchild.ts
process.send('Hello from child as string');
process.send({message: 'Hello from child as object'});

process.on('message', message => {
	// print message from parent
	console.log(message);
});
All messages are serialized using the JSC serialize API, which allows for the same set of transferrable types supported by postMessage and structuredClone, including strings, typed arrays, streams, and objects.
/icons/typescript.svgchild.ts
// send a string
process.send('Hello from child as string');

// send an object
process.send({message: 'Hello from child as object'});
See Docs > API > Child processes for complete documentation.
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