Multiple git configurations depending on the repository path

For my work on Debian, i want to use my debian.org email address, while for my personal projects i want to use my gmail.com address.

One way to change the user.email git config value is to git config --local in every repo, but that's tedious, error-prone and doesn't scale very well with many repositories (and the chances to forget to set the right one on a new repo are ~100%).

The solution is to use the git-config ability to include extra configuration files, based on the repo path, by using includeIf:

Content of ~/.gitconfig:

[user]
    name = Sandro Tosi
    email = <personal.address>@gmail.com

[includeIf "gitdir:~/deb/"]
    path = ~/.gitconfig-deb

Every time the git path is in ~/deb/ (which is where i have all Debian repos) the file ~/.gitconfig-deb will be included; its content:

[user]
    email = morph@debian.org

That results in my personal address being used on all repos not part of Debian, where i use my Debian email address. This approach can be extended to every other git configuration values.