allows the to perform various low-level commands regardless of the system's state
to enable the syreq keys, do :
reboot with proper syncing : hold the keys : (ctrl+alt+printscreen) and type : r e i s u b
- ctrl+alt+printscreen+b = immediately reboot the system, without unmounting or syncing filesystems
- ctrl+alt+printscreen+c = perform a system crash
- ctrl+alt+printscreen+d = display all currently held Locks
- ctrl+alt+printscreen+e = send the SIGTERM signal to all processes except PID 1
- ctrl+alt+printscreen+f = calls oom_kill
- ctrl+alt+printscreen+i = send the SIGKILL signal to all processes except init
- ctrl+alt+printscreen+k = kill all processes on the current virtual console
- ctrl+alt+printscreen+r = switch the keyboard from raw mode to XLATE mode
- ctrl+alt+printscreen+s = sync all mounted filesystems
- ctrl+alt+printscreen+u = remount all mounted filesystems in read-only mode