Plugins
Nu can be extended using plugins. Plugins behave much like Nu's built-in commands, with the added benefit that they can be added separately from Nu itself.
Nu plugins are executables; Nu launches them as needed and communicates with them over stdin, stdout, and stderr. Nu plugins can use either JSON or MSGPACK as their communication encoding.
Downloading and installing a plugin
WARNING
Please note that plugin installation methods are still under heavy development and that the following workflow will be refined before the release of 1.0. The nupm official package manager should simplify installation in the future when it becomes ready for general use.
To install a plugin on your system, you first need to make sure that the plugin uses the same version of Nu as your system.
> version
Find plugins that have the exact same Nushell version either on crates.io, online git repositories or awesome-nu
. You can find which version the plugin uses by checking the Cargo.toml file.
To install a plugin by name from crates.io, run:
> cargo install plugin_name
If you chose to download the git repository instead, run this when inside the cloned repository:
> cargo install --path .
This will create a binary file that can be used to register the plugin.
Keep in mind that when installing using crates.io, the binary can be saved in different locations depending on how your system is set up. A typical location is in the users's home directory under .cargo/bin.
Registering a plugin
To enable an installed plugin, call the register
command to tell Nu where to find it. As you do, you'll need to also tell Nushell what encoding the plugin uses.
Please note that the plugin name needs to start with nu_plugin_
, Nu uses the name prefix to detect plugins.
Linux+macOS:
> register ./my_plugins/nu_plugin_cool
Windows:
> register .\my_plugins\nu_plugin_cool.exe
When register
is called:
- Nu launches the plugin, and waits for the plugin to tell Nu which communication encoding it should use
- Nu sends it a "Signature" message over stdin
- The plugin responds via stdout with a message containing its signature (name, description, arguments, flags, and more)
- Nu saves the plugin signature in the file at
$nu.plugin-path
, so registration is persisted across multiple launches
Once registered, the plugin is available as part of your set of commands:
> help commands | where command_type == "plugin"
Updating a plugin
When updating a plugin, it is important to run register
again just as above to load the new signatures from the plugin and allow Nu to rewrite them to the plugin file ($nu.plugin-path
).
Managing plugins
To view the list of plugins you have installed:
> plugin list
╭───┬─────────┬────────────┬─────────┬───────────────────────┬───────┬───────────────────────────────╮
│ # │ name │ is_running │ pid │ filename │ shell │ commands │
├───┼─────────┼────────────┼─────────┼───────────────────────┼───────┼───────────────────────────────┤
│ 0 │ gstat │ true │ 1389890 │ .../nu_plugin_gstat │ │ ╭───┬───────╮ │
│ │ │ │ │ │ │ │ 0 │ gstat │ │
│ │ │ │ │ │ │ ╰───┴───────╯ │
│ 1 │ inc │ false │ │ .../nu_plugin_inc │ │ ╭───┬─────╮ │
│ │ │ │ │ │ │ │ 0 │ inc │ │
│ │ │ │ │ │ │ ╰───┴─────╯ │
│ 2 │ example │ false │ │ .../nu_plugin_example │ │ ╭───┬───────────────────────╮ │
│ │ │ │ │ │ │ │ 0 │ nu-example-1 │ │
│ │ │ │ │ │ │ │ 1 │ nu-example-2 │ │
│ │ │ │ │ │ │ │ 2 │ nu-example-3 │ │
│ │ │ │ │ │ │ │ 3 │ nu-example-config │ │
│ │ │ │ │ │ │ │ 4 │ nu-example-disable-gc │ │
│ │ │ │ │ │ │ ╰───┴───────────────────────╯ │
╰───┴─────────┴────────────┴─────────┴───────────────────────┴───────┴───────────────────────────────╯
Plugins stay running while they are in use, and are automatically stopped by default after a period of time of inactivity. This behavior is managed by the plugin garbage collector. To manually stop a plugin:
> plugin stop gstat
If we check plugin list
again, we can see that it is no longer running:
> plugin list | where name == gstat | select name is_running
╭───┬───────┬────────────╮
│ # │ name │ is_running │
├───┼───────┼────────────┤
│ 0 │ gstat │ false │
╰───┴───────┴────────────╯
Plugin garbage collector
Nu comes with a plugin garbage collector, which automatically stops plugins that are not actively in use after a period of time (by default, 10 seconds). This behavior is fully configurable:
$env.config.plugin_gc = {
# Settings for plugins not otherwise specified:
default: {
enabled: true # set to false to never automatically stop plugins
stop_after: 10sec # how long to wait after the plugin is inactive before stopping it
}
# Settings for specific plugins, by plugin name
# (i.e. what you see in `plugin list`):
plugins: {
gstat: {
stop_after: 1min
}
inc: {
stop_after: 0sec # stop as soon as possible
}
stream_example: {
enabled: false # never stop automatically
}
}
}
For more information on exactly under what circumstances a plugin is considered to be active, see the relevant section in the contributor book.
Removing a plugin
To remove a plugin, edit the $nu.plugin-path
file and remove all of the register
commands referencing the plugin you want to remove, including the signature argument.
Examples
Nu's main repo contains example plugins that are useful for learning how the plugin protocol works:
Debugging
The simplest way to debug a plugin is to print to stderr; plugins' standard error streams are redirected through Nu and displayed to the user.
Help
Nu's plugin documentation is a work in progress. If you're unsure about something, the #plugins channel on the Nu Discord is a great place to ask questions!
More details
The plugin chapter in the contributor book offers more details on the intricacies of how plugins work from a software developer point of view.