Conditional git config includes

Sometimes we want to use different git configurations for different sub-directories. For client work, for example, we might want to use another email address for our commits. While this could be accomplished by modifying the local git configuration in each repository, there is another way to solve the problem in one stroke: conditional includes.

Using the include keyword, we can include other configuration files. With includeIf, we can supply a condition that must be met. There are many options, but one of the most useful ones is gitdir. If all work related projects are contained in a directory called work (be that in ~/work or ~/dev/work or somewhere else entirely), we can use this statement to include work-specific configuration for those projects:

[includeIf "gitdir:work/"]
  path = config-work

The path to the config file to include is relative to the main configuration file, unless an absolute path is given. Within it, we can override settings from the main file, e.g.:

[user]
  email = [e-mail]

Source: man git-config