$ git config --global user.name "John Doe"
$ git config --system user.name "John Doe"
[includeIf "gitdir:~/company_a/"]
path = .gitconfig-company_a
[includeIf "gitdir:~/company_b/"]
path = .gitconfig-company_b
[user]
name = John Smith
email = john.smith@companya.net
[user]
name = John Smith
email = js@companyb.com