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kimmobrunfeldt
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Description

Run commands concurrently. Like `npm run watch-js & npm run watch-less` but better.

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Concurrently

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Run multiple commands concurrently. Like

npm run watch-js & npm run watch-less
but better.

Table of contents - Why - Install - Usage - Programmatic Usage - FAQ

Why

I like task automation with npm but the usual way to run multiple commands concurrently is

npm run watch-js & npm run watch-css
. That's fine but it's hard to keep on track of different outputs. Also if one process fails, others still keep running and you won't even notice the difference.

Another option would be to just run all commands in separate terminals. I got tired of opening terminals and made concurrently.

Features:

  • Cross platform (including Windows)
  • Output is easy to follow with prefixes
  • With
    --kill-others
    switch, all commands are killed if one dies
  • Spawns commands with spawn-command

Install

The tool is written in Node.js, but you can use it to run any commands.

npm install -g concurrently

or if you are using it from npm scripts:

npm install concurrently --save

Usage

Remember to surround separate commands with quotes:

bash
concurrently "command1 arg" "command2 arg"

Otherwise concurrently would try to run 4 separate commands:

command1
,
arg
,
command2
,
arg
.

In package.json, escape quotes:

"start": "concurrently \"command1 arg\" \"command2 arg\""

NPM run commands can be shortened:

concurrently "npm:watch-js" "npm:watch-css" "npm:watch-node"

Equivalent to:

concurrently -n watch-js,watch-css,watch-node "npm run watch-js" "npm run watch-css" "npm run watch-node"

NPM shortened commands also support wildcards. Given the following scripts in package.json:

{
    //...
    "scripts": {
        // ...
        "watch-js": "...",
        "watch-css": "...",
        "watch-node": "...",
        // ...
    },
    // ...
}
concurrently "npm:watch-*"

Equivalent to:

concurrently -n js,css,node "npm run watch-js" "npm run watch-css" "npm run watch-node"

Any name provided for the wildcard command will be used as a prefix to the wildcard

part of the script name:

concurrently -n w: npm:watch-*

Equivalent to:

concurrently -n w:js,w:css,w:node "npm run watch-js" "npm run watch-css" "npm run watch-node"

Good frontend one-liner example here.

Help:

concurrently [options] 

General -m, --max-processes How many processes should run at once. New processes only spawn after all restart tries of a process. [number] -n, --names List of custom names to be used in prefix template. Example names: "main,browser,server" [string] --name-separator The character to split on. Example usage: concurrently -n "styles|scripts|server" --name-separator "|" [default: ","] -r, --raw Output only raw output of processes, disables prettifying and concurrently coloring. [boolean] -s, --success Return exit code of zero or one based on the success or failure of the "first" child to terminate, the "last child", or succeed only if "all" child processes succeed. [choices: "first", "last", "all"] [default: "all"] --no-color Disables colors from logging [boolean]

Prefix styling -p, --prefix Prefix used in logging for each process. Possible values: index, pid, time, command, name, none, or a template. Example template: "{time}-{pid}" [string] [default: index or name (when --names is set)] -c, --prefix-colors Comma-separated list of chalk colors to use on prefixes. If there are more commands than colors, the last color will be repeated. - Available modifiers: reset, bold, dim, italic, underline, inverse, hidden, strikethrough - Available colors: black, red, green, yellow, blue, magenta, cyan, white, gray - Available background colors: bgBlack, bgRed, bgGreen, bgYellow, bgBlue, bgMagenta, bgCyan, bgWhite See https://www.npmjs.com/package/chalk for more information. [string] [default: "gray.dim"] -l, --prefix-length Limit how many characters of the command is displayed in prefix. The option can be used to shorten the prefix when it is set to "command" [number] [default: 10] -t, --timestamp-format Specify the timestamp in moment/date-fns format. [string] [default: "yyyy-MM-dd HH:mm:ss.SSS"]

Input handling -i, --handle-input Whether input should be forwarded to the child processes. See examples for more information.[boolean] --default-input-target Identifier for child process to which input on stdin should be sent if not specified at start of input. Can be either the index or the name of the process. [default: 0]

Killing other processes -k, --kill-others kill other processes if one exits or dies [boolean] --kill-others-on-fail kill other processes if one exits with non zero status code [boolean]

Restarting --restart-tries How many times a process that died should restart. [number] [default: 0] --restart-after Delay time to respawn the process, in milliseconds. [number] [default: 0]

Options: -h, --help Show help [boolean] -v, -V, --version Show version number [boolean]

Examples:

  • Output nothing more than stdout+stderr of child processes

    $ concurrently --raw "npm run watch-less" "npm run watch-js"

  • Normal output but without colors e.g. when logging to file

    $ concurrently --no-color "grunt watch" "http-server" > log

  • Custom prefix

    $ concurrently --prefix "{time}-{pid}" "npm run watch" "http-server"

  • Custom names and colored prefixes

    $ concurrently --names "HTTP,WATCH" -c "bgBlue.bold,bgMagenta.bold" "http-server" "npm run watch"

  • Send input to default

    $ concurrently --handle-input "nodemon" "npm run watch-js" rs # Sends rs command to nodemon process

  • Send input to specific child identified by index

    $ concurrently --handle-input "npm run watch-js" nodemon 1:rs

  • Send input to specific child identified by name

    $ concurrently --handle-input -n js,srv "npm run watch-js" nodemon srv:rs

  • Shortened NPM run commands

    $ concurrently npm:watch-node npm:watch-js npm:watch-css

  • Shortened NPM run command with wildcard

    $ concurrently npm:watch-*

For more details, visit https://github.com/kimmobrunfeldt/concurrently

Programmatic Usage

concurrently can be used programmatically by using the API documented below:

concurrently(commands[, options])

  • commands
    : an array of either strings (containing the commands to run) or objects with the shape
    { command, name, prefixColor, env }
    .
  • options
    (optional): an object containing any of the below:
    • defaultInputTarget
      : the default input target when reading from
      inputStream
      . Default:
      0
      .
    • inputStream
      : a
      Readable
      stream
      to read the input from, eg
      process.stdin
      .
    • killOthers
      : an array of exitting conditions that will cause a process to kill others. Can contain any of
      success
      or
      failure
      .
    • maxProcesses
      : how many processes should run at once.
    • outputStream
      : a
      Writable
      stream
      to write logs to. Default:
      process.stdout
      .
    • prefix
      : the prefix type to use when logging processes output. Possible values:
      index
      ,
      pid
      ,
      time
      ,
      command
      ,
      name
      ,
      none
      , or a template (eg
      [{time} process: {pid}]
      ). Default: the name of the process, or its index if no name is set.
    • prefixLength
      : how many characters to show when prefixing with
      command
      . Default:
      10
    • raw
      : whether raw mode should be used, meaning strictly process output will be logged, without any prefixes, colouring or extra stuff.
    • successCondition
      : the condition to consider the run was successful. If
      first
      , only the first process to exit will make up the success of the run; if
      last
      , the last process that exits will determine whether the run succeeds. Anything else means all processes should exit successfully.
    • restartTries
      : how many attempts to restart a process that dies will be made. Default:
      0
      .
    • restartDelay
      : how many milliseconds to wait between process restarts. Default:
      0
      .
    • timestampFormat
      : a date-fns format to use when prefixing with
      time
      . Default:
      yyyy-MM-dd HH:mm:ss.ZZZ

Returns: a

Promise
that resolves if the run was successful (according to
successCondition
option), or rejects, containing an array of objects with information for each command that has been run, in the order that the commands terminated. The objects have the shape
{ command, index, exitCode }
, where
command
is the object passed in the
commands
array and
index
its index there. Default values (empty strings or objects) are returned for the fields that were not specified.

Example:

const concurrently = require('concurrently');
concurrently([
    'npm:watch-*',
    { command: 'nodemon', name: 'server' },
    { command: 'deploy', name: 'deploy', env: { PUBLIC_KEY: '...' } }
], {
    prefix: 'name',
    killOthers: ['failure', 'success'],
    restartTries: 3,
}).then(success, failure);

FAQ

  • Process exited with code null?

    From Node child_process documentation,

    exit
    event:

    This event is emitted after the child process ends. If the process terminated normally, code is the final exit code of the process, otherwise null. If the process terminated due to receipt of a signal, signal is the string name of the signal, otherwise null.

    So null means the process didn't terminate normally. This will make concurrent to return non-zero exit code too.

  • Does this work with the npm-replacements yarn or pnpm?

    Yes! In all examples above, you may replace "

    npm
    " with "
    yarn
    " or "
    pnpm
    ".

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