nu_plugin_bash_env

A Bash environment plugin for Nushell.

For instructions on how to use this plugin, see the Nushell book.

In summary, build the crate and add the resulting nu_plugin_bash_env executable as a plugin using plugin add, then plugin use.

For users of Nix, this is now installable as a flake (see below).

The plugin reads the specified environment file (if any) and evaluates variables from stdin (if any) and returns any new or changed environment variables as a record, suitable for passing to Nu's load-env.

Plugin Version Compatability

Since Nushell 0.91.0 the plugin protocol was enhanced and now requires version compatability between plugins and Nushell itself.

The following versions are compatible.

If you find a new version of Nushell rejects this plugin as incompatible, please report an issue.

Dependencies

The script uses jq for output formatting. Previous versions required at least jq version 1.7, but that may be no longer the case.

Also I suspect at least Bash version 5.1.

Since version 0.15.0, this plugin uses bash-env-json instead of the previously bundled bash_env.sh script. However, this is fetched and embedded at build time, so there is no difference at runtime.

Examples

Simple Usage

> bash-env tests/simple.env
╭───┬───╮
│ B │ b │
│ A │ a │
╰───┴───╯

> echo $env.A
Error: nu::shell::name_not_found

  × Name not found


> bash-env tests/simple.env | load-env

> echo $env.A
a
> echo $env.B
b


> bash-env tests/simple.env
╭──────────────╮
│ empty record │
╰──────────────╯

# no new or changed environment variables, so nothing returned

> ssh-agent | bash-env
Agent pid 98985
╭───────────────┬───────────────────────────────────╮
│ SSH_AUTH_SOCK │ /tmp/ssh-XXXXXXFIMT9y/agent.98982 │
│ SSH_AGENT_PID │ 98985                             │
╰───────────────┴───────────────────────────────────╯

Exporting Shell Variables

The plugin supports --export for exporting shell variables into the environment.

> echo "ABC=123" | bash-env
╭──────────────╮
│ empty record │
╰──────────────╯

> echo "export ABC=123" | bash-env
╭─────┬─────╮
│ ABC │ 123 │
╰─────┴─────╯

> echo "ABC=123" | bash-env --export [ABC]
╭─────┬─────╮
│ ABC │ 123 │
╰─────┴─────╯

> bash-env /etc/os-release
╭──────────────╮
│ empty record │
╰──────────────╯

> bash-env --export [ID PRETTY_NAME] /etc/os-release
╭─────────────┬──────────────────────╮
│ ID          │ nixos                │
│ PRETTY_NAME │ NixOS 24.05 (Uakari) │
╰─────────────┴──────────────────────╯

Escaping Special Characters

Care has been taken to escape any special characters.

> bash-env `tests/Ming's "menu" of (merciless) monstrosities.env`
╭───────────┬──────────────────────────────────────────────────────╮
│ QUOTE     │ "Well done!" is better than "Well said!"             │
│ SPACEMAN  │ One small step for a man ...                         │
│ MIXED_BAG │ Did the sixth sheik's sixth sheep say "baa", or not? │
╰───────────┴──────────────────────────────────────────────────────╯

> bash-env `tests/Ming's "menu" of (merciless) monstrosities.env` | load-env
> echo $env.QUOTE
"Well done!" is better than "Well said!"

Implementation

Prior to 0.13.0 this plugin was written in Bash, with the Nu plugin protocol done by hand using jq, with insights from the api sub-directory which contained a Rust program to produce what is required, using the official Nu plugin library. This was too onerous to maintain through the evolution of the protocol, so was abandoned.

Since 0.13.0, the plugin is written in Rust, with the much simplified Bash script embedded.

By default the embedded Bash script is extracted at runtime into a temporary directory. This behaviour may be overridden by setting the ``NU_PLUGIN_BASH_ENV_JSON` environment variable, which is then expected to resolve to the path of the pre-installed script.

Logging

Logging is supported via the Rust tracing-subscriber crate, with log-level defined by the environment variable NU_PLUGIN_BASH_ENV_LOG.

Nix flake

The plugin is installable from its flake using Nix Home Manager.

See my own Home Manager flake and nushell module for hints how to achieve this. Note in particular the requirement for each-time plugin registration.

Notes

All local variables in the script are prefixed with underscore, in an attempt to mitigate Bash's inability to distinguish variables local to the shell and environment variables, but this is by no means bulletproof.

Future work

• unsetting an environment variable ought to be possible