I like to specify a different git author email for personal projects and work projects. This can be done per-repo with git config user.name and git config user.email, but it can be easy to forget as you clone repos. Here is how I used direnv to accomplish this automatically.

direnv loads shell environment variables based on .envrc files. Git’s author email can be set with GIT_COMMITTER_EMAIL and GIT_AUTHOR_EMAIL. This means that we can use direnv to set these variables for specific folders.

I keep my work projects under a single directory (~/work/a2 at the time of this writing). The simplest way to setup the necessary variables is to add the following to ~/work/a2/.envrc:

export GIT_AUTHOR_EMAIL=me@work.com
export GIT_COMMITTER_EMAIL=me@work.com

If you need more custom settings, you could also add a custom function to ~/.direnvrc that can then be used in .envrc files:

set_git_author() {
  local email="$1" name="$2"

  if [[ -z "$email" ]] || [[ -z "$name" ]]; then
    >&2 echo "Couldn't set git author!"
    return 1
  fi

  export GIT_COMMITTER_NAME="$name"
  export GIT_COMMITTER_EMAIL="$email"
  export GIT_AUTHOR_NAME="$name"
  export GIT_AUTHOR_EMAIL="$email"
}

With the custom function approach, your .envrc file would look like:

set_git_author me@work.com "Not Josh"

Once you have edited .envrc, you must allow it to be executed by direnv by running direnv allow, in my case:

direnv allow ~/work/a2/.envrc

Now, any time I cd ~/work/a2, the custom email I’ve specified is set when I use git commit. direnv will search parent directories for .envrc files, so this works in any subdirectory (eg: ~/work/a2/cool-project). In any other directory, git will use the default user.email I have configured in ~/.gitconfig.

Update, 07/27/22: I came across this post (Hacker News thread) that outlines something similar, using [includeIf "gitdir:PATH] in your ~.gitconfig. I may need to give this a try as I’ve found the approach above breaks down if a sub-project also has an .envrc file.