title: get linux shell name
body: <p>In my program I need to output to user which shell he is using. So in file <code>/etc/udate-motd.d/00-header</code> I wrote <code>printf "$SHELL"</code> but the problem is that even when I switching my shell to zsh, $SHELL is still equal to /bin/bash. I searched through the internet and found that I can bo it by using <code>MyShell='ps -hp $$'</code>, and here is again a problem. When I use it <code>MyShell</code> is a string with number of processes (<code>/etc/update-motd.d/00-header</code> is also there) but there no word <code>zsh</code>.</p>
  
  <p>So how can I understand which shell use the logging in person.</p>