Concurrently

Version: 1.0.0 (previous stable)

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

It also works on Windows. You can tune your npm scripts to work across platforms.

Install

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

npm install -g concurrently

Usage

Remember to surround separate commands with quotes, like this:

concurrent "command1 arg" "command2 arg"

Otherwise concurrent would try to run 4 separate commands: command1, arg, command2, arg.

Help:

  Usage: concurrent [options] <command ...>

  Options:

    -h, --help                    output usage information
    -V, --version                 output the version number
    -k, --kill-others             kill other processes if one exits or dies
    --no-color                    disable colors from logging
    -p, --prefix <prefix>         prefix used in logging for each process.
    Possible values: index, pid, command, none. Default: index

    -r, --raw                     output only raw output of processes, disables prettifying and colors
    -l, --prefix-length <length>  limit how many characters of the command is displayed in prefix.
    The option can be used to shorten long commands.
    Works only if prefix is set to "command". Default: 10


  Examples:

   - Kill other processes if one exits or dies

       $ concurrent --kill-others "grunt watch" "http-server"

   - Output nothing more than stdout+stderr of child processes

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

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

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

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

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.

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.

NPM Issue

Previously I thought this could fix some problems I had with watching scripts and this readme said:

When running watch or serve tasks, I'd recommend to use --kill-others option:

concurrent --kill-others "npm run watch-js" "npm run watch-less"

That way, if for some reason e.g. your watch-less died, you would notice it easier.

However NPM didn't work as I hoped it would. See this issue.