Why I can't use 'startx' command to start X Server on RHEL7 with "X window system" package group?

Environment

• Red Hat Enterprise Linux 7
• xorg-x11-xinit-1.3.2-14.el7.x86_64

Issue

• Can't start the X server using the startx command, while the basic xinit command works.

• The server is running RHEL7, installed as a minimal server, only the core and "X window system" package group plus xterm are installed. But when try to run startx command, it fails with following error:

     xinit: connection to X server lost
  
     waiting for X server to shut down (EE) Server terminated successfully (0). 
     Closing log file.
  

• xinit command without any options starts fine, but startx with the default RHEL7 system xinitrc script fails. What is causing this problem?

Resolution

Note: This solution only applies if you are intending to use 'twm' or 'mwm' graphical environments. For questions regarding installing a full-feature GUI, such as Gnome, please see How to install a graphical user interface (GUI) for Red Hat Enterprise Linux

• Install "motif" package on system and replace /usr/bin/twm with /usr/bin/mwm in /etc/X11/xinit/xinitrc and /etc/X11/xinit/Xclients both files.
  Eg:

• The /etc/X11/xinit/xinitrc file after replacing /usr/bin/twm with /usr/bin/mwm should have following entry:

  <snip>
  if [ -f $HOME/.Xclients ]; then
  exec $CK_XINIT_SESSION $SSH_AGENT $HOME/.Xclients || \
  exec $CK_XINIT_SESSION $SSH_AGENT $HOME/.Xclients elif [ -f /etc/X11/xinit/Xclients ]; then
  exec $CK_XINIT_SESSION $SSH_AGENT /etc/X11/xinit/Xclients || \
  exec $CK_XINIT_SESSION $SSH_AGENT /etc/X11/xinit/Xclients else
  # Failsafe settings.  Although we should never get here
  # (we provide fallbacks in Xclients as well) it can't hurt.
  [ -x /usr/bin/xsetroot ] && /usr/bin/xsetroot -solid '#222E45'
  [ -x /usr/bin/xclock ] && /usr/bin/xclock -geometry 100x100-5+5 &
  [ -x /usr/bin/xterm ] && xterm -geometry 80x50-50+150 &
  [ -x /usr/bin/mwm ] && /usr/bin/mwm
  fi
  </snip>
  

• The /etc/X11/xinit/Xclients script file after replacing /usr/bin/twm with /usr/bin/mwm should have following entry:

      <snip>
      # Failsafe.
      # these files are left sitting around by TheNextLevel.
      rm -f $HOME/Xrootenv.0
   
      # Argh! Nothing good is installed. Fall back to twm {
      # gosh, neither fvwm95 nor fvwm2 is available; 
       # fall back to failsafe settings
       [ -x /usr/bin/xsetroot ] && /usr/bin/xsetroot -solid '#222E45'
  
       if [ -x /usr/bin/xclock ] ; then
  	 /usr/bin/xclock -geometry 100x100-5+5 &
       fi
       if [ -x /usr/bin/xterm ] ; then
          /usr/bin/xterm -geometry 80x50-50+150 &
       fi
       if [ -x /usr/bin/firefox -a -f /usr/share/doc/HTML/index.html ]; then
  	/usr/bin/firefox /usr/share/doc/HTML/index.html &
       fi
       if [ -x /usr/bin/mwm ] ; then
  	exec /usr/bin/mwm
       fi
       }
      </snip>
  

• After above changes try to run startx command.

Root Cause

• The startx script is a front end to xinit. To determine the client to run, startx first looks for a file called .xinitrc in the user's home directory. If that is not found, it uses the file xinitrc in the xinit library directory(/etc/X11/xinit/). The /etc/X11/xinit/xinitrc file have following entry:

     <snip>
  
     if [ -f $HOME/.Xclients ]; then
        exec $CK_XINIT_SESSION $SSH_AGENT $HOME/.Xclients || \
        exec $CK_XINIT_SESSION $SSH_AGENT $HOME/.Xclients
     elif [ -f /etc/X11/xinit/Xclients ]; then
        exec $CK_XINIT_SESSION $SSH_AGENT /etc/X11/xinit/Xclients || \
        exec $CK_XINIT_SESSION $SSH_AGENT /etc/X11/xinit/Xclients
     else
       # Failsafe settings.  Although we should never get here
       # (we provide fallbacks in Xclients as well) it can't hurt.
       [ -x /usr/bin/xsetroot ] && /usr/bin/xsetroot -solid '#222E45'
       [ -x /usr/bin/xclock ] && /usr/bin/xclock -geometry 100x100-5+5 &
       [ -x /usr/bin/xterm ] && xterm -geometry 80x50-50+150 &
       [ -x /usr/bin/twm ] && /usr/bin/twm
     fi
     </snip>
  

In above output we can see that /etc/X11/xinit/Xclients script is being called.

• The /etc/X11/xinit/Xclients script have following entry:

    <snip>
    # Failsafe.
    # these files are left sitting around by TheNextLevel.
    rm -f $HOME/Xrootenv.0
    # Argh! Nothing good is installed. Fall back to twm
    {
    # gosh, neither fvwm95 nor fvwm2 is available; 
    # fall back to failsafe settings
    [ -x /usr/bin/xsetroot ] && /usr/bin/xsetroot -solid '#222E45'
    if [ -x /usr/bin/xclock ] ; then
        /usr/bin/xclock -geometry 100x100-5+5 &
     fi
     if [ -x /usr/bin/xterm ] ; then
         /usr/bin/xterm -geometry 80x50-50+150 &
     fi
     if [ -x /usr/bin/firefox -a -f /usr/share/doc/HTML/index.html ]; then
   /usr/bin/firefox /usr/share/doc/HTML/index.html &
     fi
     if [ -x /usr/bin/twm ] ; then
   exec /usr/bin/twm
     fi
     }
     </snip>
  

• The above scripts have entry for /usr/bin/twm, which is deprecated in RHEL7. There is no package which provides this binary in RHEL7.

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