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The core monitoring functionality of forever without the CLI


You can also use forever from inside your own Node.js code:

  var forever = require('forever-monitor');
  var child = new (forever.Monitor)('your-filename.js', {
    max: 3,
    silent: true,
    args: []
  child.on('exit', function () {
    console.log('your-filename.js has exited after 3 restarts');

Spawning a non-node process

You can spawn non-node processes too. Either set the command key in the options hash or pass in an Array in place of the file argument like this:

  var forever = require('forever-monitor');
  var child = forever.start([ 'perl', '-le', 'print "moo"' ], {
    max : 1,
    silent : true

Options available when using Forever in node.js

There are several options that you should be aware of when using forever. Most of this configuration is optional.

    // Basic configuration options
    'silent': false,            // Silences the output from stdout and stderr in the parent process
    'uid': 'your-UID',          // Custom uid for this forever process. (default: autogen)
    'pidFile': 'path/to/', // Path to put pid information for the process(es) started
    'max': 10,                  // Sets the maximum number of times a given script should run
    'killTree': true,           // Kills the entire child process tree on `exit`
    // These options control how quickly forever restarts a child process
    // as well as when to kill a "spinning" process
    'minUptime': 2000,     // Minimum time a child process has to be up. Forever will 'exit' otherwise.
    'spinSleepTime': 1000, // Interval between restarts if a child is spinning (i.e. alive < minUptime).
    // Command to spawn as well as options and other vars
    // (env, cwd, etc) to pass along
    'command': 'perl',         // Binary to run (default: 'node')
    'args':    ['foo','bar'],  // Additional arguments to pass to the script,
    'sourceDir': 'script/path',// Directory that the source script is in
    // Options for restarting on watched files.
    'watch': true,               // Value indicating if we should watch files.
    'watchIgnoreDotFiles': null, // Whether to ignore file starting with a '.'
    'watchIgnorePatterns': null, // Ignore patterns to use when watching files.
    'watchDirectory': null,      // Top-level directory to watch from. You can provide multiple watchDirectory options to watch multiple directories (e.g. for cli: forever start -w='app' -w='some_other_directory' app\index.js)
    // All or nothing options passed along to `child_process.spawn`.
    'spawnWith': {
      customFds: [-1, -1, -1], // that forever spawns.
      setsid: false,
      uid: 0,      // Custom UID
      gid: 0,      // Custom GID
      shell: false // Windows only - makes forever spawn in a shell
    // More specific options to pass along to `child_process.spawn` which
    // will override anything passed to the `spawnWith` option
    'env': { 'ADDITIONAL': 'CHILD ENV VARS' },
    'cwd': '/path/to/child/working/directory',
    // Log files and associated logging options for this instance
    'logFile': 'path/to/file', // Path to log output from forever process (when daemonized)
    'outFile': 'path/to/file', // Path to log output from child stdout
    'errFile': 'path/to/file', // Path to log output from child stderr
    // ### function parseCommand (command, args)
    // #### @command {String} Command string to parse
    // #### @args    {Array}  Additional default arguments
    // Returns the `command` and the `args` parsed from
    // any command. Use this to modify the default parsing
    // done by 'forever-monitor' around spaces.
    'parser': function (command, args) {
      return {
        command: command,
        args:    args

Events available when using an instance of Forever in node.js

Each forever object is an instance of the Node.js core EventEmitter. There are several core events that you can listen for:

  • error [err]: Raised when an error occurs
  • start [process, data]: Raised when the target script is first started.
  • stop [process]: Raised when the target script is stopped by the user
  • restart [forever]: Raised each time the target script is restarted
  • exit [forever]: Raised when the target script actually exits (permanently).
  • stdout [data]: Raised when data is received from the child process' stdout
  • stderr [data]: Raised when data is received from the child process' stderr

Typical console output

When running the forever CLI tool, it produces debug outputs about which files have changed / how processes exited / etc. To get a similar behaviour with forever-monitor, add the following event listeners:

const child = new (forever.Monitor)('your-filename.js');
child.on('watch:restart', function(info) {
    console.error('Restarting script because ' + info.file + ' changed');
child.on('restart', function() {
    console.error('Forever restarting script for ' + child.times + ' time');
child.on('exit:code', function(code) {
    console.error('Forever detected script exited with code ' + code);


  $ npm install forever-monitor

Run Tests

  $ npm test

License: MIT

Author: Charlie Robbins

Contributors: Fedor Indutny, James Halliday, Charlie McConnell, Maciej Malecki

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