远程按机箱上的Reset键-Remotely Force a Reboot
by Gavin W. Burris
If you need to remotely hard-reset your Linux system because of a read-only file system, try Magic SysRq:
# echo 1 >/proc/sys/kernel/sysrq ; echo b >/proc/sysrq-trigger
This will enable SYSRQ and power cycle the system, like hitting the reset button. This is obviously a last resort, only when a clean shutdown will not work.