The Child Process module in Node.js is used to spawn child processes in a manner that is both simple and efficient. These child processes are independent of the main event loop, and they can either run concurrently or in an ordered sequence.
Here’s a basic way of using it:
1. Include the Child Process Module: Begin by including the child process module with require.
\`\`\`javascript const child_process = require(‘child_process’); \`\`\`1. Create a Child Process: You can create a child process in several ways, but one of the most common is ‘spawn’.
\`\`\`javascript const child = child\_process.spawn(‘command’, [‘arg1’, ‘arg2’]); \`\`\` The ‘command’ here is the name of the command to run, and the array is a list of string arguments.1. Work with Input and Output: Child processes can input and output through their standard input (stdin), standard output (stdout), and standard error (stderr) streams. These are available on the child process object.
\`\`\`javascript child.stdout.on(‘data’, (data) => { console.log(`child stdout:\n${data}`); }); child.stderr.on(‘data’, (data) => { console.error(`child stderr:\n${data}`); }); \`\`\` In this example, we are listening to the ‘data’ events on both the stdout and stderr streams. When the child process writes to those streams, our callbacks will be invoked with the data.1. Handle ‘exit’ event: You can handle the exit event which is triggered when the child process ends.
\`\`\`javascript child.on(‘exit’, (code, signal) => { console.log(`child process exited with code ${code}, signal ${signal}`); }); \`\`\`This above example is just a basic overview. Depending on your needs, you might also want to check out ‘exec’ and ‘fork’ from child\_process module which provide more functionality.
- `exec`: Spawns a shell and runs a command within that shell, passing the stdout and stderr to a callback function when complete.
- `fork`: This is a special case of the `spawn()` functionality for spawning Node processes. It has the same options, but also has built-in communication channels.
