title: Tmux failed to connect to server error on `tmux ls` when there are no running sessions
body: <p>Just writing a quick loop to list out existing tmux sessions when I log into a server, depending on whether tmux is installed (via .bashrc on CentOS). </p>
  
  <pre><code>if rpm -q tmux; then
      echo -e "TMUX sessions running:\n"
      echo `tmux ls`
  fi
  </code></pre>
  
  <p>This works great when tmux has a session or two, but if there are no running tmux sessions, I'm getting <code>failed to connect to server: No such file or directory</code>.</p>
  
  <p>Is there a way to suppress this?</p>
  
  <p>Thanks!</p>