NAME¶

npm-exec

Synopsis¶

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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 they are installed to a folder in the npm cache, which
is added to the PATH environment variable in the executed process. A
prompt is printed (which can be suppressed by providing either --yes or
--no).

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:

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¶

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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

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

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

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:

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.

See Also¶