Handling Linux emergencies

Rebooting a machine by power cycling it is the last thing you should do!

There are a number of reasons why users should not routinely power cycle machines to get themselves out of apparently stuck situations.

There may be a less drastic method to correct the situation.
If there is a recurring problem, there is no way for the support staff to know of/look into it if you "correct" the problem in this manner without telling anyone.
If a reboot is necessary, it is possible that you or the staff may be able to reboot the machine without a power cycle.
Someone else may be running something on your machine which could be corrupted by a reboot. (Though you think of your desktop as "your own," I routinely run cron jobs as part of my usual monitoring procedure.)
A power cycle without orderly shutting down active processes may leave the files/disks in a state which could require privs to correct -- or be too corrupted to correct.

There are a number of things you can do on your Linux desktop to remedy apparently hung situations. From the "Xconf" man page:

Ctrl+Alt+Backspace: Immediately kills the server -- no questions asked.
Ctrl+Alt+Keypad-Plus: Change video mode to next one specified in the configuration file.
Ctrl+Alt+Keypad-Minus: Change video mode to previous one specified in the configuration file.
Ctrl+Alt+F1 ... F12: For BSD and Linux systems with virtual terminal support, these keystroke combinations are used to switch to virtual terminals 1 through 12, respectively.

So the first thing you might do is Ctrl+Alt+F1, log in, and poke around to see if you can kill off what may be hung. Don't forget to log off if you switch back to the server (using Ctrl+Alt+F7) and find the situation better. (Virtual terminal 7 is what the server uses by default.) If you cannot correct it that way, Ctrl+Alt+Backspace looks like it would be the next option of choice. Something not mentioned on that list, Ctrl+Alt+Delete, is more drastic, but less so than a power cycle. It produces an orderly shutdown/reboot of the machine.

So please, before resorting to power cycling a machine, try contacting support staff (or the operator at 5-2443) to let us look into a less drastic solution. And let us know if there is a repeating problem causing you to resort to such measures.

This page last updated February 17, 2005.