Git-git config

--global

For writing options:write to global ~/.gitconfig file rather than the repository .git/config
For reading options:read only from global ~/.gitconfig

--system

For writing options:write to system-wide/etc/gitconfig rather than the repository.git/config
For reading options:read only from system-wide /etc/gitconfig

--local

For writing options: write to the repository .git/config file. This is the default behavior.
For reading options: read only from the repository .git/config rather than from all available files.