shell alias to use specific identity file on git push

git-ssh-key.sh

# Example: git-ssh-key ~/path/to/identity-file git push origin master
git-ssh-key() {
  ssh_key=${1:?Usage: git-ssh-key identity-file commands...}
  shift
  GIT_SSH_COMMAND=" \
    ssh -F /dev/null \
      -o IdentitiesOnly=yes \
      -o IdentityFile=\"$ssh_key\" \
      -o UserKnownHostsFile=/dev/null \
      -o StrictHostKeyChecking=no \
    " "$@"
}