Hab

While on Mars, the crew will be living in an artificial habitat, or Hab for short.

Hab is an Oh My ZSH plugin that loads/unloads OS enviroment variables and functions automatically when:

• Changing directories
• After editing .envrc files.
• Opening new shells.

Small example

Given the following .envrc file in the folder my_project:

# file: /home/user/my_project/.envrc
export HOSTNAME="https://my.hab"

function clean_build() {
  rm -rf "$(pwd)/_build" 2> /dev/null
  echo "All cleaned!"
}

Then:

1. Loads it when cding into my_project:

   ~ $ cd my_project
   [SUCCESS]  Loaded hab [/home/user/my_project/.envrc]
   
   ~/my_project $ echo "$HOSTNAME"
   https://my.hab
   
   ~/my_project $ clean_build
   All cleaned!

2. Unloads it when cding out of my_project

   ~/my_project $ cd ..
   [WARN]  Unloaded variable HOSTNAME
   [WARN]  Unloaded function clean_build

Hab Autoload

The environment will be (re)loaded automatically every time:

• We change directory and there's a .envrc file available.
• We edit the .envrc while its environment was already loaded.
• We open a new shell in a directory with an .envrc file present.

Different Habs

Though Hab it's going to autoload .envrc automatically every time you change directories, you can manually load special environments e.g:

Given the folliwing environment files:

~/my_project $ ls -a
.
..
.envrc
.envrc.test
.envrc.dev
.envrc.prod

We could load any of them by using its extension (no extension to use the default one) e.g:

~/my_project $ hab dev
[WARN]     Unloaded variable HOSTNAME
[WARN]     Unloaded function clean_build
[SUCCESS]  Loaded hab [/home/user/my_project/.envrc.dev] (Last modified Wed 04 Mar 2020 03:42:52 PM CET)

Hab sub-commands

Though we could never run a command as everything is done automatically, there are some useful sub-commands for handling things manually as well:

• Loading environments:

  ~/my_project $ hab           # Loads .envrc
  ~/my_project $ hab dev       # Loads .envrc.dev
  ~/my_project $ hab load      # Loads .envrc
  ~/my_project $ hab load dev  # Loads .envrc.dev

• Reloading environments:

  ~/my_project $ hab reload    # Reloads current environment

• Unloading environments:

  ~/my_project $ hab unload    # Unloads current environment

• Updating Hab:

  ~ $ hab update

Note: hab command supports ZSH auto-completions.

Environment file

The environment file (defaults to .envrc) accepts a zsh subset:

• Hab can only load and unload exports and functions e.g:

  export MY_VARIABLE=42
  
  function hello() {
     echo "Hello!"
  }

• Hab ignores comments and empty lines.

Additionally, if the comment # INHERIT: true is found in the file, every sub-directory will inherit the environment file (unless there's a file that overrides it) e.g. the following file will affect any folder inside ~/my_project:

# file: ~/my_project/.envrc

# INHERIT: true
export MY_VARIABLE=42

Important: In order for inheritance to work, you need to load the root environment first. If you cd directly into a sub-folder without loading the root folder's environment, it won't load the environment.

The default environment file name can be customized globally by changing the value of the variable $HAB_BASE in your .zshrc file e.g:

export HAB_BASE=".env"

Installation

Just clone Hab as follows:

~ $ git clone "https://github.com/alexdesousa/hab.git" "$ZSH_CUSTOM/plugins/hab"

And add the hab to your plugins in $HOME/.zshrc file:

autoload -U +X compinit && compinit
autoload -U +X bashcompinit && bashcompinit
autoload -U add-zsh-hook

plugins=(
  hab
)

Note: The autoloads are necessary for auto-completions and hook installation.

Author

Alexander de Sousa.

License

Hab is released under the MIT License. See the LICENSE file for further details.