I have a number of git repos on remote systems (e.g. GitLab) where my laptop’s pub key is already registered for a certain other account not associated with the aforementioned git repos.
Thus, I usually have to
GIT_SSH_COMMAND='ssh -i <path/to/some/private/key>' git <command> so as to communicate with these repos under the correct identity.
I might be a slowpoke, but after the 500th time doing so, I learned that I could do this:
git config core.sshCommand "ssh -i /path/to/some/private/key"
to save myself from having to provide that env var every.damn.time.
And after the 1000th time doing so, I decided to blog it down so my muscle memory can make room for other stuff.