Difference between revisions of "SysRq"
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| + | There is a bit of a trick to using the '''Magic SysRq''' key sequence. The trick is to hold the '''Alt''' key during the entire process. Press '''Alt''' first; hold it; press the '''SysRq''' button; then press whatever key you want. Finally, you can release the '''Alt''' key. | ||
| − | + | Output will not go to an X terminal. It will be printed on the console. Press Ctrl-Alt-F1 to switch view to the console. | |
| − | + | One some keyboards (especially Microsoft), you may find a key called '''F Lock'''. This is a stupid key. It's almost like they added a new CapsLock key except that there is no indicator to show that it is turned on. Often you need to press this once before you start. If you switch to a text console you may find that you cannot switch back to the X Window platform. Press '''F Lock''' once again to restore the function of the function keys. | |
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| − | One some keyboards (especially Microsoft), you may find a key called | ||
== SysRq output == | == SysRq output == | ||
Revision as of 12:59, 26 November 2012
There is a bit of a trick to using the Magic SysRq key sequence. The trick is to hold the Alt key during the entire process. Press Alt first; hold it; press the SysRq button; then press whatever key you want. Finally, you can release the Alt key.
Output will not go to an X terminal. It will be printed on the console. Press Ctrl-Alt-F1 to switch view to the console.
One some keyboards (especially Microsoft), you may find a key called F Lock. This is a stupid key. It's almost like they added a new CapsLock key except that there is no indicator to show that it is turned on. Often you need to press this once before you start. If you switch to a text console you may find that you cannot switch back to the X Window platform. Press F Lock once again to restore the function of the function keys.
Contents
SysRq output
The output of SysRq is logged to the console. If you have debugging set very low then you might not see anything. You can run `dmesg` to see the output or you can increase log visibility by using a SysRq command. Press the following keys to set log visibility to a high level
Alt SysRq 9
Send SysRq without keyboard
You can bypass the keyboard magic keys simply be writing the command code that want to execute to the following file:
echo h > /proc/sysrq-trigger
Enable / Disable SysRq
Enable, write a 1. To disable, write 0:
echo 1 > /proc/sys/kernel/sysrq
Freezing and unfreezing
Notes
Note: Sometimes called SysReq and Sys Request.
