@npmcli/run-script

Run a lifecycle script for a package (descendant of npm-lifecycle)

USAGE

``js
const runScript = require('@npmcli/run-script')

runScript({
// required, the script to run
event: 'install',

// extra args to pass to the command, defaults to []
args: [],

// required, the folder where the package lives
path: '/path/to/package/folder',

// optional, these paths will be put at the beginning of $PATH, even
// after run-script adds the node_modules/.bin folder(s) from
// process.cwd(). This is for commands like npm init, npm exec,
// and npx to make sure manually installed packages come before
// anything that happens to be in the tree in process.cwd().
binPaths: [
'/path/to/npx/node_modules/.bin',
'/path/to/npm/prefix/node_modules/.bin',
],

// optional, defaults to /bin/sh on unix, or cmd.exe on windows
scriptShell: '/bin/bash',

// optional, passed directly to @npmcli/promise-spawn which defaults it to true
// return stdout and stderr as strings rather than buffers
stdioString: false,

// optional, additional environment variables to add
// note that process.env IS inherited by default
// Always set:
// - npm_package_json The package.json file in the folder
// - npm_lifecycle_event The event that this is being run for
// - npm_lifecycle_script The script being run
// The fields described in https://github.com/npm/rfcs/pull/183
env: {
npm_package_from: 'foo@bar',
npm_package_resolved: 'https://registry.npmjs.org/foo/-/foo-1.2.3.tgz',
npm_package_integrity: 'sha512-foobarbaz',
},

// defaults to 'pipe'. Can also pass an array like you would to node's
// exec or spawn functions. Note that if it's anything other than
// 'pipe' then the stdout/stderr values on the result will be missing.
// npm cli sets this to 'inherit' for explicit run-scripts (test, etc.)
// but leaves it as 'pipe' for install scripts that run in parallel.
stdio: 'inherit',

// print the package id and script, and the command to be run, like:
// > somepackage@1.2.3 postinstall
// > make all-the-things
})
.then(({ code, signal, stdout, stderr, pkgid, path, event, script }) => {
// do something with the results
})
.catch(er => {
// command did not work.
// er is decorated with:
// - code
// - signal
// - stdout
// - stderr
// - path
// - pkgid (name@version string)
// - event
// - script
})
`

API

Call the exported runScript function with an options object.

Returns a promise that resolves to the result of the execution. Promise
rejects if the execution fails (exits non-zero) or has any other error.
Rejected errors are decorated with the same values as the result object.

If the stdio options mean that it'll have a piped stdin, then the stdin is
ended immediately on the child process. If stdin is shared with the parent
terminal, then it is up to the user to end it, of course.

$3

- code Process exit code
- signal Process exit signal
- stdout stdout data (Buffer, or String when stdioString set to true)
- stderr stderr data (Buffer, or String when stdioString set to true)
- path Path to the package executing its script
- event Lifecycle event being run
- script Command being run

If stdio is inherit this package will emit a banner with the package
name and version, event name, and script command to be run, and send it
to proc-log.output.standard. Consuming
libraries can decide whether or not to display this.

$3

- path Required. The path to the package having its script run.
- event Required. The event being executed.
- args Optional, default []. Extra arguments to pass to the script.
- env Optional, object of fields to add to the environment of the
subprocess. Note that process.env IS inherited by default These are
always set:
- npm_package_json The package.json file in the folder
- npm_lifecycle_event The event that this is being run for
- npm_lifecycle_script The script being run
- The package.json fields described in
RFC183.
- scriptShell Optional, defaults to /bin/sh on Unix, defaults to
env.ComSpec or cmd on Windows. Custom script to use to execute the
command.
- stdio Optional, defaults to 'pipe'. The same as the stdio argument
passed to child_process functions in Node.js. Note that if a stdio
output is set to anything other than pipe, it will not be present in
the result/error object.
- cmd Optional. Override the script from the package.json with
something else, which will be run in an otherwise matching environment.
- stdioString Optional, passed directly to @npmcli/promise-spawn which
defaults it to true. Return string values for stderr and stdout rather
than Buffers.

Note that this does _not_ run pre-event and post-event scripts. The
caller has to manage that process themselves.

Differences from npm-lifecycle

This is an implementation to satisfy RFC
90, RFC
77, and RFC
73.

Apart from those behavior changes in npm v7, this is also just refresh of
the codebase, with modern coding techniques and better test coverage.

Functionally, this means:

- Output is not dumped to the top level process's stdio by default.
- Less stuff is put into the environment.
- It is not opinionated about logging. (So, at least with the logging
framework in npm v7.0 and before, the caller has to call
log.disableProgress() and log.enableProgress() at the appropriate
times, if necessary.)
- The directory containing the node executable is _never_ added to the
PATH environment variable. (Ie, --scripts-prepend-node-path is
effectively always set to false.) Doing so causes more unintended side
effects than it ever prevented.
- Hook scripts are not run by this module. If the caller wishes to run
hook scripts, then they can override the default package script with an
explicit cmd option pointing to the node_modules/.hook/${event}
script.

Escaping

In order to ensure that arguments are handled consistently, this module
writes a temporary script file containing the command as it exists in
the package.json, followed by the user supplied arguments having been
escaped to ensure they are processed as literal strings. We then instruct
the shell to execute the script file, and when the process exits we remove
the temporary file.

In Windows, when the shell is cmd, and when the initial command in the script
is a known batch file (i.e. something.cmd) we double escape additional
arguments so that the shim scripts npm installs work correctly.

The actual implementation of the escaping is in lib/escape.js`.