exec

[Ray Andrews <rayandrews@xxxxxxxxxxx>]

    I've just recently come across 'exec' in a
      few scripts.  No familiarity with it.  Running this:
      
      echo before exec
      exec echo exec itself
      echo after exec
      
      ... I find that whether in a script or a function it zaps the
      terminal and there's no such place as 'after exec'. What are the
      uses of that?  For example the script that starts xfce4
      'etc/xdg/xfce4/xinitrc' ends with this:
      
           exec xfce4-session
      
      ... so 'then what'?  Hard to put the question into words, but I
      have a sort of hanging feeling, I don't know where execution
      goes.  For that matter, neither do the xfce4 people know where it
      goes.  ( Micro rant: you have yer systemd and yer xdg and yer dbus
      and God knows what else all layered on top of each other and
      nobody knows what's actually happening.) The question arises cuz I
      want to run scripts both just before and just after an xfce4
      session but nobody knows how that might be done.  Not our problem
      here of course, but if I had some insights into 'exec' it might
      help.  When, where and why do we 'exec' things?