Safely reboot frozen linux system
Ever got stuck with frozen linux system? I love messing around with latest and greatest (never on my main machine). So every now and than system freezes beyond repair. So what do I do when that happens?
Well, this is what I do:
- for safely reboot:
Hold Alt + Prt Scr/SysRq (print button) and slowly (about 1 second betweeen each letter) type in REISUB
- for safely power off:
Hold Alt + Prt Scr/SysRq (print button) and slowly (about 1 second between each letter) type in REISUO
What is the SysRq key?
Wikipedia says: The magic SysRq key is a key combination understood by the Linux kernel, which allows the user to perform various low level commands regardless of the system’s state. It is often used to recover from freezes, or to reboot a computer without corrupting the filesystem. Read more on Wikipedia on an in-dept listing of SysRq keys and here is the short list I used:
- R: Switch the keyboard from raw mode to XLATE mode
- E: Send the SIGTERM signal to all processes except init
- I: Send the SIGKILL signal to all processes except init
- S: Sync all mounted filesystems
- U: Remount all mounted filesystems in read-only mode
- B: Immediately reboot the system, without unmounting partitions or syncing
Works for me! 🙂