Set username and email globally

git config --global user.name "John"
git config --global user.email "johndoe@gmail.com"

Check if we have set the Git username and email globally

git config --global user.name
git config --global user.email

Set username and email for a single repository

git config user.name "John"
git config user.email "johndoe@gmail.com"

Check if we have set the Git username and email locally (for a single repository)

git config user.name
git config user.email