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 and stdout or local sockets. Nu plugins can use either JSON or MessagePack 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 add 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.

Adding a plugin

To add a plugin to the plugin registry file, call the plugin add command to tell Nu where to find it.

Please note that the plugin name needs to start with nu_plugin_, Nu uses the name prefix to detect plugins.

Linux+macOS:

> plugin add ./my_plugins/nu_plugin_cool

Windows:

> plugin add .\my_plugins\nu_plugin_cool.exe

When plugin add is called, Nu runs the plugin binary and communicates via the plugin protocol in order to ensure compatibility and to get a list of all of the commands it supports. These are then saved to the plugin registry file ($nu.plugin-path) which acts as a cache.

Once added, the next time nu is started, the plugin should show up in plugin list with all of its commands are available in scope:

> help commands | where command_type == "plugin"

You can also immediately reload a plugin in the current session by calling plugin use:

> plugin use cool

It is not necessary to add plugin use to your config file. All previously added plugins are automatically loaded at startup.

Note that plugin use is a parser keyword, so when evaluating a script, it will be evaluated first. This means that while you can execute plugin add and then plugin use at the REPL on separate lines, you can't do this in a single script. If you need to run nu with a specific plugin or set of plugins without preparing a cache file, you can pass the --plugins option to nu with a list of plugin executable files:

> nu --plugins '[./my_plugins/nu_plugin_cool]'

Updating a plugin

When updating a plugin, it is important to run plugin add 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). You can then plugin use to get the updated signatures within the current session.

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, call plugin stop with its name:

> 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
        }
        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, call plugin rm with the name of the plugin you want to remove. For example, if you previously added the plugin ~/.cargo/bin/nu_plugin_gstat, its name would be gstat. To remove it:

plugin rm gstat

You can check the name of a plugin by running plugin list.

Examples

Nu's main repo contains example plugins that are useful for learning how the plugin protocol works:

• Rust
• Python

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.

Tracing

The Nu plugin protocol message stream may be captured for diagnostic purposes using trace_nu_plugin.

WARNING: trace output will accumulate for as long as the plugin is installed with the trace wrapper. Large files are possible. Be sure to remove the plugin with plugin rm when finished tracing, and reinstall without the trace wrapper.

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.