Add a Git hook to automatically verify a repository's email

December 3, 2016

I use Git a lot and I often have to switch between my personal repositories (ie: Github) and my professional (Ippon) repositories on the same laptop. My default Git email is configured to my personal email and I have often forgotten to configure it to my professional email when creating/cloning a repository for my company. Like everything in Git, this can be automated to avoid mistakes.

In this post, I will show how I use a Git hook to check the email configured in any repository before every commit.

Email configuration per repositories:

When you first installed Git you probably have set your username and email globally with these commands:

$ git config --global "Raphael Brugier"
$ git config --global ""

You can override this values per repository:

$ cd some-ippon-project
$ git config ""
## print the configuration
$ git config

Git hooks

Git hooks are scripts that Git executes before or after Git commands. For example: commit, push, rebase, …

They are located in every Git repository in the .git/hooks/ folder. By default, Git creates hooks suffixed with “.sample” To create a custom hook, create a new executable script without the suffix for the hook you want to create and add the Bash code for your needs:

$ vim .git/hooks/pre-commit
## add the hook code as any bash script
$ chmod +x .git/hooks/pre-commit

Global Git hooks

Since its version 2.9, Git offers an option to share the hooks globally between the repositories. I prefer this option to duplicating hooks in every repository, even if you could use templates to automatically copy them in every new repository.

Create a hooks folder, for example in your dotfiles, and configure Git globally to use this folder as the hooks folder for every repository:

$ mkdir -p ~/dotfiles/_git/hooks/
$ git config --global core.hooksPath ~/dotfiles/_git/hooks/

Git has added the option in your global Git config:

$ cat ~/.gitconfig
    name = Raphael Brugier
    email =
    hooksPath = ~/dotfiles/_git/templates/hooks/

Check email hook

The goal is now to use a hook to validate the email set in the repository before committing.

I follow a simple convention to differentiate my personal and professional repositories. My professional repositories are located on ~/devs/ippon and my personal on ~/devs/github/ or ~/devs/projects/

Write a bash script to check the email configured based on the repository’s path as a pre-commit hook :

$ vim ~/dotfiles/_git/hooks/pre-commit
if [[ $PWD == *"ippon"* ]] # 1)
  EMAIL=$(git config
  if [[ $EMAIL == *"ippon"* ]] # 2)
    echo "";
    echo "email not configured to Ippon in Ippon directory";
    echo "run:"
    echo '   git config ""'
    echo ''
    exit 1; # 3)
  1. check if the current path contains “ippon”
  2. check if the configured email also contains “ippon”
  3. if not, exit the script with an error. This will cancel the commit.


Test the hook is working in a new repository:

$ mkdir -p ~/devs/ippon/testhook/
$ cd ~/devs/ippon/testhook
$ git init
$ git commit -m "test"
> email not configured to Ippon in Ippon directory
> run:
>   git config ""


Git hooks are powerful to automate tests and avoid mistakes. Other common usages of hooks are to trigger tests before a commit or a deployment after a push.

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