Linux Base System Hung
Do your utmost to avoid forcing a power down. You may leave the disk
in a half-written state and it may not reboot successfully.
Try the following steps, in order, until you have wakened the system
from its narcosis.
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Is it really hung? Perhaps it is just a "work slowdown".
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Try the obvious, like unplugging the device you plugged in just before
it hung. Try to determine what changed before it hung.
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If X11 is running, do ctrl-alt-F1, which should bring you to
the console window. From there you can login and try to determine which process
is hanging the system. Some useful commands are:
- tail /var/log/messages
- top
- ps -ef
- ps aux
If you think the gnome X11 session is the culprit, you can look for and
shut down the gnome session with these commands:
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ps -ef | fgrep gnome-session
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pkill -HUP gnome-session
To return to the X11 login window, do alt-F7.
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If it hangs early in the boot sequence, you may be able to use the DOS three
finger salute: ctrl-alt-del.
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Otherwise, if all else fails, use the following three-finger-chords
with the SysRq key (labeled as Print/SysRq), by first pressing and
holding the Alt key, then SysRq and then 's', 'u' or 'b'.
Do these chords, in succession:
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alt-sysrq-s (syncs the disk)
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alt-sysrq-u (unmounts disks, then remounts read-only)
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alt-sysrq-b (boots)
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If the kernel is completely hung, and none of the above solutions work, you
can force a power off, by holding down the power button until it powers
off. Good luck on the reboot.