{"id":1540,"date":"2017-05-26T08:44:57","date_gmt":"2017-05-26T12:44:57","guid":{"rendered":"https:\/\/easy-admin.ca\/?p=1540"},"modified":"2017-07-12T20:56:23","modified_gmt":"2017-07-13T00:56:23","slug":"understanding-the-sysrq-key-the-magic-key-to-control-linux","status":"publish","type":"post","link":"https:\/\/easy-admin.ca\/index.php\/2017\/05\/26\/understanding-the-sysrq-key-the-magic-key-to-control-linux\/","title":{"rendered":"Understanding the SysRq Key \u2013 The Magic Key To Control Linux"},"content":{"rendered":"

Linux do crash. It is not so frequent, but it happens. You know what to do when an application refuses to obey, but if everything fails, the last solution is using the supreme power on Linux: the magic SysRq<\/em> key. By using this key with a combination of \u201cAlt\u201d and another letter, you will be able to make your computer respond no matter what. It was already evoked, but a little explanation does not hurt, and the more you know, the more prepared you will be when facing a real problem. Also, understanding the individual effect is always better than just repeating a combo learned by heart.<\/p>\n

How To Activate The Magic Key<\/h2>\n

As said before, the magic key is super handy. But first, you have to activate this functionality if it is not already done. To check, use the command<\/p>\n

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cat \/proc\/sys\/kernel\/sysrq<\/pre>\n<\/div>\n<\/div>\n
If it returns a 1, the Magic Key is working. If it is a 0, you will need to activate it. In most cases, if you want to activate it temporarily, you can try<\/p>\n
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sudo echo \"1\" > \/proc\/sys\/kernel\/sysrq<\/pre>\n<\/div>\n<\/div>\n
But this did not work for me. So under Archlinux, I used instead:<\/p>\n
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sudo sysctl kernel.sysrq=1<\/pre>\n<\/div>\n<\/div>\n
Note that this will be only temporary. If you want the Magic Key to work even after a reboot, the best way is to edit the file \u201c\/etc\/sysctl.conf\u201d, so that the line<\/p>\n
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kernel.sysrq = 0<\/pre>\n<\/div>\n<\/div>\n
becomes<\/p>\n
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kernel.sysrq = 1<\/pre>\n<\/div>\n<\/div>\n
List of Useful Combinations<\/h2>\n
The whole point of using the Magic SysRq key is to combine it with the \u201cAlt\u201d key and another letter in order to trigger a particular function, even if your computer seems frozen. To begin, you should know that this System Request key is usually sharing its location with the \u201cPrint Scrn\u201d key at the top right of your keyboard. Above the \u201cInsert\u201d key, and left to \u201cScroll Lock.\u201d<\/p>\n
\"\"<\/p>\n
As you can guess, the effect of the combination depends on which letter key is used. Here is a non-exhaustive list of letter you can use to obtain an interesting result.<\/p>\n