Use two or more usernames/SSH keys for remote git repos

git-multiple-ssh-keys.md

##Using Multiple SSH Keys With Git

Unless specified, Github and other remote repositories will use the default SSH keys, usually at /Users/<you>/.ssh/id_rsa. The SSH key is associated with the email you entered when you created it, so in order to use a different email/username/ssh key combo for another remote repository, you'll have to do the following:

1. Create a new SSH key following the same directions here: https://help.github.com/articles/generating-ssh-keys, but when prompted to enter the file name, name it something like /Users/<you>/.ssh/id_rsa_somethingelse instead.
2. Look for a file in ~/.ssh/ called 'config'. If it doesn't exist, create one. (No extension).
3. Add this to the file and save it:

Host <someremotedomain>
    User git  
    Hostname <someremotedomain>  
    IdentityFile ~/.ssh/id_rsa_somethingelse

4. Register your new SSH key by opening terminal and typing: ssh-add ~/.ssh/id_rsa_somethingelse
5. Add (or delete then re-add) a remote url for the repository: git remote add <some alias> <remote ssh url with someremotedomain in it>

Any time you add a remote url to a local project with <someremotedomain> in the remote url, the ssh key used will be the key specified in the ssh config file for that Host.