18.4 Objective 3: Identify and Terminate Runaway X Applications

This short Objective highlights what can be a frustrating aspect of working with X. You're likely to sometimes experience problems with X, perhaps even an X server crash. Usually the applications that were running during the X session exit immediately. However, some X client programs may leave processes running after the X server terminates. These programs may consume resources on your system and need to be identified.

As an example of this behavior, it's possible for the Netscape browser to remain after an X session crash. If this happens, you'll probably note that your system is sluggish. Use the top utility to identify the offending program and kill or killall to terminate it.

If your X session hangs completely, you can use a virtual terminal^[7] to log in again and kill runaway processes or even the X server. Use Ctrl-Alt-F2 or Ctrl-Alt-F3 to switch to terminals 2 or 3, respectively.

^[7] Virtual terminals are configured in /etc/inittab. Most Linux distributions preconfigure six virtual terminals.

On the Exam Unlike some other operating systems where the GUI is an integral part of the system, an X server is simply a special process with other client processes depending upon it. If the X process terminates or has a problem, it's likely that the X clients will also fail in some way, including failing to exit cleanly. Remember that the termination of X may leave X clients active.