In the rare cases that a Linux machine freezes, it can usually be rebooted with the Ctrl-Alt-Backspace key combination. However, if this doesn’t work you can try raising the elephant:

To be able to use this functionality, your kernel needs to be compiled with the CONFIG_MAGIC_SYSRQ option on. If your kernel was compiled with this option, entering the following command on the command line should cause the same path to be echoed out:

ls /proc/sys/kernel/sysrq

A simple mnemonic to remember the combination of keys to raise the elephant is “Raising Skinny Elephants Is Utterly Boring” (RSEIUB). Hold down the left Alt and the SysRq (sometimes labelled “Print Screen“) keys and press the following letters in this order, making sure that you give a few seconds pause between keystrokes:

  • R - put keyboard in raw mode
  • S - sync the disk
  • E - terminate all processes
  • I - kill all processes
  • U - remount all filesystems read-only
  • B - reboot the system

If your system uses an ext3 or ReiserFS filesystem and it requests to do a filesystem check while rebooting, you should let it automatically recover the journal by not pressing any key when you are prompted to press “Y“.

Share this article: These icons link to social bookmarking sites where readers can share and discover new web pages.
  • Twitter
  • GatorPeeps
  • Digg
  • Reddit
  • muti.co.za
  • DZone
  • del.icio.us
  • StumbleUpon
  • Technorati
  • Ma.gnolia
  • Slashdot

Related posts:

  1. Ubuntu Linux Quick Tip - Mount a Samba (Windows) file share to a folder
  2. Checking kernel, architecture, and release (distribution) information on Linux
  3. Configuring a Vodafone 3G modem on Ubuntu Linux 9.04 (Jaunty Jackalope)
  4. Linux Quick Tip: Renew a machine’s DHCP lease with dhclient
  5. Reusing commands with different arguments on a Bash command line