envrc - Auto source bash .envrc of your workspace

Wny?

Firstly, direnv doesn't officially support alias at the moment.

Secondly,

direnv is actually creating a new bash process to load the stdlib, direnvrc and .envrc, and only exports the environment diff back to the original shell.

However, envrc is simpler. It spawns a new interactive bash and load .envrc. When you cd out of the directory, the shell exits and returns terminal back to the original shell.

Install

• cargo install envrc
• Add PROMPT_COMMAND='eval "$(envrc bash)"' to the end of your bashrc

Usage

$ mkdir foo
$ 
$ echo 'echo in foo directory' > foo/.envrc
$ 
$ cd foo
  envrc: spawning new /bin/bash
  envrc: loading [/home/roxma/test/envrc/foo/.envrc]
  in foo directory
$ 
$ cd ..
  envrc: exit [/home/roxma/test/envrc/foo/.envrc]

$ envrc
  envrc 0.2
  Rox Ma roxma@qq.com
  auto source .envrc of your workspace

  USAGE:
      envrc [SUBCOMMAND]

  FLAGS:
      -h, --help       Prints help information
      -V, --version    Prints version information

  SUBCOMMANDS:
      allow    Grant permission to envrc to load the .envrc
      bash     for bashrc: PROMPT_COMMAND='eval "$(envrc bash)"'
      deny     Remove the permission
      help     Prints this message or the help of the given subcommand(s)
      prune    Remove expired or non-existing-file permissions

Note: Take care of your background jobs before getting out of .envrc.

.envrc tips

• export WORKSPACE_DIR=$(readlink -f "$(dirname "${BASH_SOURCE[0]}")") for .envrc to locate its directory.
• exec bash to reload the modifed .envrc

.bashrc config

# If the `.envrc` is allowed, but not sourced for 1d since last unload, It
# will be considered expired
export ENVRC_ALLOW_DURATION=$((60*60*24))
PROMPT_COMMAND='eval "$(envrc bash)"'

Why not bash/python?

The first working commit is written in python. But there's noticeable time lag with the python version on my PC. Rewriting it with perl doesn't help either. Then I decided to switch to rust.

$ time envrc.py bash-prompt-command >/dev/null
real    0m0.079s
user    0m0.044s
sys     0m0.004s

I have also tried a pure bash implementation. It works better than the python implementation, since most of the python overhead is its startup time. Most of the bash overhead is fork/exec of sub-processes and it's way slower than the rust implementation. Read #1 for more information.