How to Use Multiple Git Configs on One Computer

Imagine you have used only a personal GitHub account so far.

Now you want two identities on one computer: one for personal work and one for work-related repos.

Create two gitconfig files:

cd $HOME
cp .gitconfig .gitconfig-personal
mv .gitconfig .gitconfig-work

# change the email address to your work address

code .gitconfig-work

Then create a new ~/.gitconfig:

code .gitconfig

Put this into it:

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

Source: How to Use Multiple Git Configs on One Computer