Man page - npm-exec(1)

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Manual

NPM-EXEC

NAME
Synopsis
Description
npx vs npm exec
Configuration
Examples
Workspaces support
Filtering workspaces
Compatibility with Older npx Versions
A note on caching
prefer-online
prefer-offline
offline
workspace
workspaces
See Also

---

NAME

npm-exec

Synopsis

<!-- AUTOGENERATED USAGE DESCRIPTIONS -->

Description

This command allows you to run an arbitrary command from an npm package
(either one installed locally, or fetched remotely), in a similar context
as running it via npm run .

Run without positional arguments or --call , this allows you to
interactively run commands in the same sort of shell environment that
package.json scripts are run. Interactive mode is not supported in CI
environments when standard input is a TTY, to prevent hangs.

Whatever packages are specified by the --package option will be
provided in the PATH of the executed command, along with any locally
installed package executables. The --package option may be
specified multiple times, to execute the supplied command in an environment
where all specified packages are available.

If any requested packages are not present in the local project
dependencies, then a prompt is printed, which can be suppressed by
providing either --yes or --no . When standard input is not a TTY or a
CI environment is detected, --yes is assumed. The requested packages are
installed to a folder in the npm cache, which is added to the PATH
environment variable in the executed process.

Package names provided without a specifier will be matched with whatever
version exists in the local project. Package names with a specifier will
only be considered a match if they have the exact same name and version as
the local dependency.

If no -c or --call option is provided, then the positional arguments
are used to generate the command string. If no --package options
are provided, then npm will attempt to determine the executable name from
the package specifier provided as the first positional argument according
to the following heuristic:

•

If the package has a single entry in its bin field in package.json ,

or if all entries are aliases of the same command, then that command
will be used.

•

If the package has multiple bin entries, and one of them matches the

unscoped portion of the name field, then that command will be used.

•

If this does not result in exactly one option (either because there are

no bin entries, or none of them match the name of the package), then
npm exec exits with an error.

To run a binary other than the named binary, specify one or more
--package options, which will prevent npm from inferring the package from
the first command argument.

npx vs npm exec

When run via the npx binary, all flags and options must be set prior to
any positional arguments. When run via npm exec , a double-hyphen --
flag can be used to suppress npm’s parsing of switches and options that
should be sent to the executed command.

For example:

$ npx foo@latest bar --package=@npmcli/foo

In this case, npm will resolve the foo package name, and run the
following command:

$ foo bar --package=@npmcli/foo

Since the --package option comes after the positional arguments, it is
treated as an argument to the executed command.

In contrast, due to npm’s argument parsing logic, running this command is
different:

$ npm exec foo@latest bar --package=@npmcli/foo

In this case, npm will parse the --package option first, resolving the
@npmcli/foo package. Then, it will execute the following command in that
context:

$ foo@latest bar

The double-hyphen character is recommended to explicitly tell npm to stop
parsing command line options and switches. The following command would
thus be equivalent to the npx command above:

$ npm exec -- foo@latest bar --package=@npmcli/foo

Configuration

<!-- AUTOGENERATED CONFIG DESCRIPTIONS -->

Examples

Run the version of tap in the local dependencies, with the provided
arguments:

$ npm exec -- tap --bail test/foo.js
$ npx tap --bail test/foo.js

Run a command other than the command whose name matches the package name
by specifying a --package option:

$ npm exec --package=foo -- bar --bar-argument
# ˜ or ˜
$ npx --package=foo bar --bar-argument

Run an arbitrary shell script, in the context of the current project:

$ npm x -c ’eslint && say "hooray, lint passed"’
$ npx -c ’eslint && say "hooray, lint passed"’

Workspaces support

You may use the workspace or
workspaces configs in order to run an
arbitrary command from an npm package (either one installed locally, or fetched
remotely) in the context of the specified workspaces.
If no positional argument or --call option is provided, it will open an
interactive subshell in the context of each of these configured workspaces one
at a time.

Given a project with configured workspaces, e.g:

.
+-- package.json
‘-- packages
+-- a
| ‘-- package.json
+-- b
| ‘-- package.json
‘-- c
‘-- package.json

Assuming the workspace configuration is properly set up at the root level
package.json file. e.g:

{
"workspaces": [ "./packages/*" ]
}

You can execute an arbitrary command from a package in the context of each of
the configured workspaces when using the
workspaces config options, in this example
we’re using eslint to lint any js file found within each workspace folder:

npm exec --ws -- eslint ./*.js

Filtering workspaces

It’s also possible to execute a command in a single workspace using the
workspace config along with a name or directory path:

npm exec --workspace=a -- eslint ./*.js

The workspace config can also be specified multiple times in order to run a
specific script in the context of multiple workspaces. When defining values for
the workspace config in the command line, it also possible to use -w as a
shorthand, e.g:

npm exec -w a -w b -- eslint ./*.js

This last command will run the eslint command in both ./packages/a and
./packages/b folders.

Compatibility with Older npx Versions

The npx binary was rewritten in npm v7.0.0, and the standalone npx
package deprecated at that time. npx uses the npm exec
command instead of a separate argument parser and install process, with
some affordances to maintain backwards compatibility with the arguments it
accepted in previous versions.

This resulted in some shifts in its functionality:

	•		Any npm config value may be provided.
	•		To prevent security and user-experience problems from mistyping package

names, npx prompts before installing anything. Suppress this
prompt with the -y or --yes option.

	•		The --no-install option is deprecated, and will be converted to --no .
	•		Shell fallback functionality is removed, as it is not advisable.
	•		The -p argument is a shorthand for --parseable in npm, but shorthand

for --package in npx. This is maintained, but only for the npx
executable.

•

The --ignore-existing option is removed. Locally installed bins are

always present in the executed process PATH .

•

The --npm option is removed. npx will always use the npm it ships

with.

	•		The --node-arg and -n options are removed.
	•		The --always-spawn option is redundant, and thus removed.
	•		The --shell option is replaced with --script-shell , but maintained

in the npx executable for backwards compatibility.

A note on caching

The npm cli utilizes its internal package cache when using the package
name specified. You can use the following to change how and when the
cli uses this cache. See npm cache for more on
how the cache works.

prefer-online

Forces staleness checks for packages, making the cli look for updates
immediately even if the package is already in the cache.

prefer-offline

Bypasses staleness checks for packages. Missing data will still be
requested from the server. To force full offline mode, use offline .

offline

Forces full offline mode. Any packages not locally cached will result in
an error.

workspace

	•		Default:
	•		Type: String (can be set multiple times)

Enable running a command in the context of the configured workspaces of the
current project while filtering by running only the workspaces defined by
this configuration option.

Valid values for the workspace config are either:

	•		Workspace names
	•		Path to a workspace directory
	•		Path to a parent workspace directory (will result to selecting all of the

nested workspaces)

This value is not exported to the environment for child processes.

workspaces

	•		Alias: --ws
	•		Type: Boolean
	•		Default: false

Run scripts in the context of all configured workspaces for the current
project.

See Also

	•		npm run-script
	•		npm scripts
	•		npm test
	•		npm start
	•		npm restart
	•		npm stop
	•		npm config
	•		npm workspaces
	•		npx

---