There are situations where you want to have different configurations for git depending on the repository. Preferable without manual configure it for every repository.
To get that result you can load additional configuration depending on the remote url.
I use it to load a different configuration for the repositories that I have for my employer. This is because I use a different email address and different GPG signingkey for my work.
A part of your default git config has your email and signingkey. (That is in the ~/.gitconfig file.)
[user]
name = Tobias van Beek
email = t.vanbeek@example.com
signingkey = 15C136467A0141D0
The repositories for my employer are all in the same group on GitLab. That gives me the option to use one includeIf with the GitLab url.
[includeIf "hasconfig:remote.*.url:git@gitlab.com:my-employer/**"]
path = .gitconfig-employer
And in my .gitconfig-employer file I have the config that is different from the default configurations.
[user]
email = tobias.van.beek@employer.example.com
signingkey = EBF1B56EC1AAE2E6
If I run git config -l in a repository for my employer I have both email and signingkey configurations. First the default one and then the configuration from my employer config file. Git use the last found configuration, that means I get the
There are more options for the includeIf, see: https://git-scm.com/docs/git-config#_conditional_includes