concurrently
Run multiple commands concurrently.
Like npm run watch-js & npm run watch-less but better.
Table of Contents
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-othersswitch, all commands are killed if one dies - Spawns commands with spawn-command
Installation
concurrently can be installed in the global scope (if you'd like to have it available and use it on the whole system) or locally for a specific package (for example if you'd like to use it in the scripts section of your package):
| npm | Yarn | pnpm | Bun | |
|---|---|---|---|---|
| Global | npm i -g concurrently |
yarn global add concurrently |
pnpm add -g concurrently |
bun add -g concurrently |
| Local* | npm i -D concurrently |
yarn add -D concurrently |
pnpm add -D concurrently |
bun add -d concurrently |
* It's recommended to add concurrently to devDependencies as it's usually used for developing purposes. Please adjust the command if this doesn't apply in your case.
Usage
Note The
concurrentlycommand is now also available under the shorthand aliasconc.
The tool is written in Node.js, but you can use it to run any commands.
Remember to surround separate commands with quotes:
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"Exclusion is also supported. Given the following scripts in package.json:
{
// ...
"scripts": {
"lint:js": "...",
"lint:ts": "...",
"lint:fix:js": "...",
"lint:fix:ts": "..."
// ...
}
// ...
}# Running only lint:js and lint:ts
# with lint:fix:js and lint:fix:ts excluded
concurrently "npm:lint:*(!fix)"Good frontend one-liner example here.
Help:
concurrently [options] <command ...>
General
-m, --max-processes How many processes should run at once.
Exact number or a percent of CPUs available (for example "50%").
New processes only spawn after all restart tries
of a process. [string]
-n, --names List of custom names to be used in prefix
template.
Example names: "main,browser,server" [string]
--name-separator The character to split <names> on. Example usage:
-n "styles|scripts|server" --name-separator "|"
[default: ","]
-s, --success Which command(s) must exit with code 0 in order
for concurrently exit with code 0 too. Options
are:
- "first" for the first command to exit;
- "last" for the last command to exit;
- "all" for all commands;
- "command-{name}"/"command-{index}" for the
commands with that name or index;
- "!command-{name}"/"!command-{index}" for all
commands but the ones with that name or index.
[default: "all"]
-r, --raw Output only raw output of processes, disables
prettifying and concurrently coloring. [boolean]
--no-color Disables colors from logging [boolean]
--hide Comma-separated list of processes to hide the
output.
The processes can be identified by their name or
index. [string] [default: ""]
-g, --group Order the output as if the commands were run
sequentially. [boolean]
--timings Show timing information for all processes.
[boolean] [default: false]
-P, --passthrough-arguments Passthrough additional arguments to commands
(accessible via placeholders) instead of treating
them as commands. [boolean] [default: false]
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,
any hex values for colors (e.g. #23de43) or auto for
an automatically picked color
- Available background colors: bgBlack, bgRed,
bgGreen, bgYellow, bgBlue, bgMagenta, bgCyan, bgWhite
See https://www.npmjs.com/package/chalk for more
information. [string] [default: "reset"]
-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]
--kill-signal Signal to send to other processes if one exits or dies.
(SIGTERM/SIGKILL, defaults to SIGTERM) [string]
Restarting
--restart-tries How many times a process that died should restart.
Negative numbers will make the process restart forever.
[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"
- Auto varying colored prefixes
$ concurrently -c "auto" "npm run watch" "http-server"
- Mixing auto and manual colored prefixes
$ concurrently -c "red,auto" "npm run watch" "http-server" "echo hello"
- Configuring via environment variables with CONCURRENTLY_ prefix
$ CONCURRENTLY_RAW=true CONCURRENTLY_KILL_OTHERS=true concurrently "echo
hello" "echo world"
- 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 (make sure to wrap it in quotes!)
$ concurrently "npm:watch-*"
- Exclude patterns so that between "lint:js" and "lint:fix:js", only "lint:js"
is ran
$ concurrently "npm:*(!fix)"
- Passthrough some additional arguments via '{<number>}' placeholder
$ concurrently -P "echo {1}" -- foo
- Passthrough all additional arguments via '{@}' placeholder
$ concurrently -P "npm:dev-* -- {@}" -- --watch --noEmit
- Passthrough all additional arguments combined via '{*}' placeholder
$ concurrently -P "npm:dev-* -- {*}" -- --watch --noEmit
For more details, visit https://github.com/open-cli-tools/concurrently
API
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, cwd }. -
options(optional): an object containing any of the below:cwd: the working directory to be used by all commands. Can be overriden per command. Default:process.cwd().defaultInputTarget: the default input target when reading frominputStream. Default:0.handleInput: whentrue, reads input fromprocess.stdin.inputStream: aReadablestream to read the input from. Should only be used in the rare instance you would like to stream anything other thanprocess.stdin. OverrideshandleInput.pauseInputStreamOnFinish: by default, pauses the input stream (process.stdinwhenhandleInputis enabled, orinputStreamif provided) when all of the processes have finished. If you need to read from the input stream afterconcurrentlyhas finished, set this tofalse. (#252).killOthers: an array of exitting conditions that will cause a process to kill others. Can contain any ofsuccessorfailure.maxProcesses: how many processes should run at once.outputStream: aWritablestream 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.prefixColors: a list of colors or a string as supported by chalk and additional styleautofor an automatically picked color. If concurrently would run more commands than there are colors, the last color is repeated, unless if the last color value isautowhich means following colors are automatically picked to vary. Prefix colors specified per-command take precedence over this list.prefixLength: how many characters to show when prefixing withcommand. Default:10raw: whether raw mode should be used, meaning strictly process output will be logged, without any prefixes, coloring or extra stuff. Can be overriden per command.successCondition: the condition to consider the run was successful. Iffirst, only the first process to exit will make up the success of the run; iflast, 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 withtime. Default:yyyy-MM-dd HH:mm:ss.ZZZadditionalArguments: list of additional arguments passed that will get replaced in each command. If not defined, no argument replacing will happen.
Returns: an object in the shape
{ result, commands }.
result: aPromisethat resolves if the run was successful (according tosuccessConditionoption), or rejects, containing an array ofCloseEvent, in the order that the commands terminated.commands: an array of all spawnedCommands.
Example:
const concurrently = require('concurrently');
const { result } = concurrently(
[
'npm:watch-*',
{ command: 'nodemon', name: 'server' },
{ command: 'deploy', name: 'deploy', env: { PUBLIC_KEY: '...' } },
{
command: 'watch',
name: 'watch',
cwd: path.resolve(__dirname, 'scripts/watchers'),
},
],
{
prefix: 'name',
killOthers: ['failure', 'success'],
restartTries: 3,
cwd: path.resolve(__dirname, 'scripts'),
},
);
result.then(success, failure);Command
An object that contains all information about a spawned command, and ways to interact with it.
It has the following properties:
index: the index of the command among all commands spawned.command: the command line of the command.name: the name of the command; defaults to an empty string.cwd: the current working directory of the command.env: an object with all the environment variables that the command will be spawned with.killed: whether the command has been killed.state: the command's state. Can be one ofstopped: if the command was never startedstarted: if the command is currently runningerrored: if the command failed spawningexited: if the command is not running anymore, e.g. it received a close event
pid: the command's process ID.stdin: a Writable stream to the command'sstdin.stdout: an RxJS observable to the command'sstdout.stderr: an RxJS observable to the command'sstderr.error: an RxJS observable to the command's error events (e.g. when it fails to spawn).timer: an RxJS observable to the command's timing events (e.g. starting, stopping).close: an RxJS observable to the command's close events. SeeCloseEventfor more information.start(): starts the command, setting up allkill([signal]): kills the command, optionally specifying a signal (e.g.SIGTERM,SIGKILL, etc).
CloseEvent
An object with information about a command's closing event.
It contains the following properties:
command: a stripped down version ofCommand, including onlyname,command,envandcwdproperties.index: the index of the command among all commands spawned.killed: whether the command exited because it was killed.exitCode: the exit code of the command's process, or the signal which it was killed with.timings: an object in the shape{ startDate, endDate, durationSeconds }.
FAQ
-
Process exited with code null?
From Node child_process documentation,
exitevent: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 concurrently to return non-zero exit code too.
-
Does this work with the npm-replacements yarn, pnpm, or Bun?
Yes! In all examples above, you may replace "
npm" with "yarn", "pnpm", or "bun".