function is_ssh_agent_running
  if begin; test -f ~/.ssh/env; and test -z "$SSH_AGENT_PID"; end
    source ~/.ssh/env > /dev/null
  end

  if test -z "$SSH_AGENT_PID"
    return 1
  end

  ps -ef | grep $SSH_AGENT_PID | grep -v grep | grep -q ssh-agent
  return $status
end