internet-programming/lab3/node_modules/npm-run-all/docs/run-p.md

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| [index](../README.md) | [npm-run-all](npm-run-all.md) | [run-s](run-s.md) | run-p | [Node API](node-api.md) |
|-----------------------|-------------------------------|-------------------|-------|-------------------------|
# `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:
--aggregate-output - - - Avoid interleaving output by delaying printing of
each command's output until it has finished.
-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.
--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:
```json
{
"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.
```json
{
"scripts": {
"start": "run-p \"start-server -- --port {1}\" --"
}
}
```
```
$ npm run start 8080
> example@0.0.0 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](http://www.gnu.org/software/bash/manual/bashref.html#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.<br>
For example, [eslint] stops coloring under `run-p --print-label`. But [eslint] has `--color` option to force coloring, we can use it.
[glob]: https://www.npmjs.com/package/glob#glob-primer
[chalk]: https://www.npmjs.com/package/chalk
[eslint]: https://www.npmjs.com/package/eslint