March 16, 2011, 9:59 p.m.
posted by juff
If you’re using X Windows in any of its multiple guises (particularly Motif) on a workstation or PC running UNIX and are especially unlucky, X itself may freeze the entire screen. If you can get into your computer through the network, you can get rid of X Windows. Doing so makes all the programs using X go away so that you have to log in all over again. The trick is to figure out which program is X Windows. Here’s an edited ps report from a System V system:
UID PID PPID C STIME TTY TIME COMMAND johnl 24788 19593 0 Jan 18 vt01 0:00 /usr/bin/X11/xinit johnl 24789 24788 5 Jan 18 ptmx 38:10 Xgp :0
In this case, X is called Xgp because the particular computer happened to have a graphics processor running the screen.
Here’s the equivalent from a Sun workstation:
PID TT STAT TIME COMMAND 224 co IW 0:00 /bin/sh /usr/openwin/bin/openwin 228 co IW 0:00 /usr/openwin/bin/xinit -- /usr/openwin/bin/xnews :0 229 co S 149:23 /usr/openwin/bin/xnews :0 -auth /usr/johnl/.xnews
You can find out which process is X in two easy ways:
The command line has the strange code :0, which turns out to be X-ese for "the screen right there on the computer."
The amount of computer time used (in the STAT column) is large because X is, computationally speaking, a pig.
After you figure out which process is X, you can give it the old Number-Nine kill and probably be able to log back in.