foreground-child
Advanced tools
Package description
The foreground-child npm package is used to run a child process in the foreground, ensuring that signals such as SIGINT, SIGTERM, and exit codes are properly forwarded from the child process to the parent. This is particularly useful when you want to ensure that a child process is treated as if it were the main process, especially in the context of command-line tools and scripts.
Running a child process in the foreground
This feature allows you to run a child process as if it were the main process. The code sample demonstrates how to use foreground-child to run a Node.js script in the foreground.
const foregroundChild = require('foreground-child');
const cmd = 'node';
const args = ['my-script.js'];
foregroundChild(cmd, args);cross-spawn is a cross-platform solution for spawning child processes with support for handling command line arguments properly. It is similar to foreground-child in that it deals with child processes, but it does not specifically focus on running them in the foreground.
execa is a wrapper for child_process methods that provides a more user-friendly API. It supports synchronous and asynchronous execution of child processes and also allows for running processes in the foreground, similar to foreground-child, but with additional features such as promise support and result parsing.
child-process-promise provides promise-based wrappers for the child_process module. While it simplifies working with asynchronous child processes, it does not have a specific focus on running child processes in the foreground like foreground-child does.
Changelog
v2.0.0
Readme
Run a child as if it's the foreground process. Give it stdio. Exit when it exits.
Mostly this module is here to support some use cases around wrapping child processes for test coverage and such.
var foreground = require('foreground-child')
// cats out this file
var child = foreground('cat', [__filename])
// At this point, it's best to just do nothing else.
// return or whatever.
// If the child gets a signal, or just exits, then this
// parent process will exit in the same way.
A callback can optionally be provided, if you want to perform an action before your foreground-child exits:
var child = foreground('cat', [__filename], function (done) {
// perform an action.
return done()
})
The callback can return a Promise instead of calling done:
var child = foreground('cat', [__filename], async function () {
// perform an action.
})
The callback must not throw or reject.
The "normal" standard IO file descriptors (0, 1, and 2 for stdin, stdout, and stderr respectively) are shared with the child process. Additionally, if there is an IPC channel set up in the parent, then messages are proxied to the child on file descriptor 3.
However, in Node, it's possible to also map arbitrary file descriptors into a child process. In these cases, foreground-child will not map the file descriptors into the child. If file descriptors 0, 1, or 2 are used for the IPC channel, then strange behavior may happen (like printing IPC messages to stderr, for example).
Note that a SIGKILL will always kill the parent process, and never the child process, because SIGKILL cannot be caught or proxied. The only way to do this would be if Node provided a way to truly exec a process as the new foreground program in the same process space, without forking a separate child process.
FAQs
Run a child as if it's the foreground process. Give it stdio. Exit when it exits.
We found that foreground-child demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 3 open source maintainers collaborating on the project.
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