NPM-EXEC(1) General Commands Manual NPM-EXEC(1)
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 con-
text
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 envi-
ronment
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 what-
ever
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 accord-
ing
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
9.2.0 December 2022 NPM-EXEC(1)
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