Select private key to use with Git

Question

I have 2 Git servers that require 2 different SSH keys.

git clone user1@server1:blahblahblah uses ~/.ssh/id_rsa, but I need to specify which key to use depending on the server I am connecting to.

What Git command-line parameter does this job? (I am running Linux.)

Answer 1

There is another possibility. That's to set core.sshCommand, e.g.

git config --local core.sshCommand "/usr/bin/ssh -i /home/me/.ssh/id_rsa_foo" 

There's one particular scenario when this strategy is particularly useful: that's when you have multiple accounts on Github, as all accounts ssh to Github as [email protected] and it uses the ssh key to determine which Github user you are. In this case neither .ssh/config nor ssh-agent will do what you want.

Update — You cannot run the above until you have a local repository, so if you're trying to clone a remote repository, you'll need to specify the key manually as per drewbie18's answer:

git clone -c core.sshCommand="/usr/bin/ssh -i /home/me/.ssh/id_rsa_foo" [email protected]:me/repo.git 

Once you've cloned the repository you can use the git config command to set this permanently.

Answer 2

If you are connecting via SSH then the key will be controlled by an SSH parameter, not a git parameter.

SSH looks in the ~/.ssh/config file for configuration parameters. Modify that file and add IdentityFile entries for the two Git servers like this:

Host server1.whatever.com   IdentityFile /path/to/key_1 Host server2.whatever.com   IdentityFile /path/to/key_2 

This article has some more details.