direnv - unclutter your .profile
direnv command ...
direnv is an environment variable manager for your shell. It knows how to
hook into bash, zsh and fish shell to load or unload environment variables
depending on your current directory. This allows you to have project-specific
environment variables and not clutter the "~/.profile" file.
Before each prompt it checks for the existence of an .envrc file in the
current and parent directories. If the file exists, it is loaded into a bash
sub-shell and all exported variables are then captured by direnv and then made
available to your current shell, while unset variables are removed.
Because direnv is compiled into a single static executable it is fast enough to be unnoticeable on each prompt. It is also language agnostic and can be used to build solutions similar to rbenv, pyenv, phpenv, ...
$ cd ~/my_project
$ echo ${FOO-nope}
nope
$ echo export FOO=foo > .envrc
\.envrc is not allowed
$ direnv allow .
direnv: reloading
direnv: loading .envrc
direnv export: +FOO
$ echo ${FOO-nope}
foo
$ cd ..
direnv: unloading
direnv export: ~PATH
$ echo ${FOO-nope}
nopeFor direnv to work properly it needs to be hooked into the shell. Each shell has it's own extension mechanism:
Add the following line at the end of the ~/.bashrc file:
eval "$(direnv hook bash)"Make sure it appears even after rvm, git-prompt and other shell extensions that manipulate the prompt.
Add the following line at the end of the ~/.zshrc file:
eval "$(direnv hook zsh)"Add the following line at the end of the ~/.config/fish/config.fish file:
eval (direnv hook fish)Add the following line at the end of the ~/.cshrc file:
eval `direnv hook tcsh`Run:
$> direnv hook elvish > ~/.elvish/lib/direnv.elvand add the following line to your ~/.elvish/rc.elv file:
use direnvIn some target folder, create an .envrc file and add some export(1)
and unset(1) directives in it.
On the next prompt you will notice that direnv complains about the .envrc
being blocked. This is the security mechanism to avoid loading new files
automatically. Otherwise any git repo that you pull, or tar archive that you
unpack, would be able to wipe your hard drive once you cd into it.
So here we are pretty sure that it won't do anything bad. Type direnv allow .
and watch direnv loading your new environment. Note that direnv edit . is a
handy shortcut that open the file in your $EDITOR and automatically allows it
if the file's modification time has changed.
Now that the environment is loaded you can notice that once you cd out
of the directory it automatically gets unloaded. If you cd back into it it's
loaded again. That's the base of the mechanism that allows you to build cool
things.
Exporting variables by hand is a bit repetitive so direnv provides a set of
utility functions that are made available in the context of the .envrc file.
Check the direnv-stdlib(1) man page for more details. You can also define your
own extensions inside ~/.config/direnv/direnvrc or
~/.config/direnv/lib/*.sh files.
Hopefully this is enough to get you started.
Bug reports, contributions and forks are welcome.
All bugs or other forms of discussion happen on http://github.com/direnv/direnv/issues
There is also a wiki available where you can share your usage patterns or other tips and tricks https://github.com/direnv/direnv/wiki
Or drop by on the #direnv channel on FreeNode to have a chat.
MIT licence - Copyright (C) 2019 @zimbatm and contributors
direnv-stdlib(1), direnv.toml(1)