run-p.md

index	npm-run-all	run-s	run-p	Node API

run-p command

A CLI command to run given npm-scripts in parallel. This command is the shorthand of npm-run-all -p.

Usage:
    $ run-p [--help | -h | --version | -v]
    $ run-p [OPTIONS] <tasks>

    Run given npm-scripts in parallel.

    <tasks> : A list of npm-scripts' names and Glob-like patterns.

Options:
    -c, --continue-on-error  - Set the flag to continue executing other tasks
                               even if a task threw an error. 'run-p' itself
                               will exit with non-zero code if one or more tasks
                               threw error(s).
    --max-parallel <number>  - Set the maximum number of parallelism. Default is
                               unlimited.
    --aggregate-output       - Avoid interleaving output by delaying printing of
                               each command's output until it has finished.
    --npm-path <string>  - - - Set the path to npm. Default is the value of
                               environment variable npm_execpath.
                               If the variable is not defined, then it's "npm."
                               In this case, the "npm" command must be found in
                               environment variable PATH.
    -l, --print-label  - - - - Set the flag to print the task name as a prefix
                               on each line of output. Tools in tasks may stop
                               coloring their output if this option was given.
    -n, --print-name   - - - - Set the flag to print the task name before
                               running each task.
    -r, --race   - - - - - - - Set the flag to kill all tasks when a task
                               finished with zero.
    -s, --silent   - - - - - - Set 'silent' to the log level of npm.

    Shorthand aliases can be combined.
    For example, '-clns' equals to '-c -l -n -s'.

Examples:
    $ run-p watch:**
    $ run-p --print-label "build:** -- --watch"
    $ run-p -l "build:** -- --watch"
    $ run-p start-server start-browser start-electron

npm-scripts

It's "scripts" field of package.json. For example:

{
    "scripts": {
        "clean": "rimraf dist",
        "lint":  "eslint src",
        "build": "babel src -o lib"
    }
}

We can run a script with npm run command. On the other hand, this run-p command runs multiple scripts in parallel.

The following 2 commands are similar. The run-p command is shorter and available on Windows.

$ run-p lint build
$ npm run lint & npm run build

Note1: If a script exited with a non-zero code, the other scripts and those descendant processes are killed with SIGTERM (On Windows, with taskkill.exe /F /T). If --continue-on-error option is given, this behavior will be disabled.

Note2: & operator does not work on Windows' cmd.exe. But run-p works fine there.

Glob-like pattern matching for script names

We can use glob-like patterns to specify npm-scripts. The difference is one -- the separator is : instead of /.

$ run-p watch:*

In this case, runs sub scripts of watch. For example: watch:html, watch:js. But, doesn't run sub-sub scripts. For example: watch:js:index.

$ run-p watch:**

If we use a globstar **, runs both sub scripts and sub-sub scripts.

run-p reads the actual npm-script list from package.json in the current directory, then filters the scripts by glob-like patterns, then runs those.

Run with arguments

We can enclose a script name or a pattern in quotes to use arguments. The following 2 commands are similar.

$ run-p "build:* -- --watch"
$ npm run build:aaa -- --watch & npm run build:bbb -- --watch

When we use a pattern, arguments are forwarded to every matched script.

Argument placeholders

We can use placeholders to give the arguments preceded by -- to scripts.

$ run-p "start-server -- --port {1}" -- 8080

This is useful to pass through arguments from npm run command.

{
    "scripts": {
        "start": "run-p \"start-server -- --port {1}\" --"
    }
}

$ npm run start 8080

> [email protected] start /path/to/package.json
> run-p "start-server -- --port {1}" -- "8080"

There are the following placeholders:

• {1}, {2}, ... -- An argument. {1} is the 1st argument. {2} is the 2nd.
• {@} -- All arguments.
• {*} -- All arguments as combined.

Those are similar to Shell Parameters. But please note arguments are enclosed by double quotes automatically (similar to npm).

Known Limitations

• If --print-label option is given, some tools in scripts might stop coloring their output. Because some coloring library (e.g. chalk) will stop coloring if process.stdout is not a TTY. run-p changes the process.stdout of child processes to a pipe in order to add labels to the head of each line if --print-label option is given.
  For example, eslint stops coloring under run-p --print-label. But eslint has --color option to force coloring, we can use it.