Wonderful sys request

Article Title: Wonderful sys requests. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.

This technique is useful if you are using a development kernel or device driver or running code that can cause serious Kernel errors on your machine.

This technique is applicable to x86, PowerPC, or iSCSI processors in Linux, and you need at least 2.2.x or later kernels.

If your machine encounters a serious error or suddenly becomes a pile of hot parts, you can use a combination of keys to synchronize the file system and reload the file system as read-only. Restart the instance to avoid the possibility of a long file system check.

Keys of different platforms are slightly different:

X86	ALT-SYSRQ-[command key]
ISCSI	ALT-STOP-[command key]
PowerPC	ALT-Print Screen-[command key]

The command key is as follows:

S	Try to synchronize all mounted file systems
U	Try to reload all mounted file systems as read-only
B	Try to restart the system immediately (This is equivalent to pressing the reset switch of the chassis. Or power button; the process will not .)
P	Print the current Register and tag to the console
T	Print the list of current tasks and related information to the console
E	Send SIGTERM to all processes, except init
I	Send SIGKILL to all processes, except init
L	Send SIGKILL to all processes

For more information, see/usr/src/linux/Documentation/sysrq.txt to obtain other key combinations.