REISUB reboot your system

• Relevant to All editions of PCLinuxOS.

R.E.I.S.U.B.

Raising Elephants Is So Utterly Boring

R.E.I.S.U.B. is a key sequence used on Linux systems to safely reboot a frozen or unresponsive computer. It is often referred to as the "magic SysRq key" (System Request key) and allows users to perform low-level commands to safely recover or restart the system.

The acronym R.E.I.S.U.B. stands for the specific sequence of commands you can execute to reboot the system safely, even if the system is otherwise unresponsive:

R - Raw mode (take control of the keyboard back from the X server). E - End all running processes cleanly (sends SIGTERM to all processes). I - Immediately kill all processes (sends SIGKILL to all processes). S - Sync the disk (flushes data to disk to prevent data loss). U - Unmount all file systems (remounts all filesystems as read-only). B - Boot (reboots the system).

How to Use R.E.I.S.U.B. Safely

Hold Alt and SysRq, and then press each letter separately in the order of R-E-I-S-U-B. However, often the SysRq key is a dual purpose key which needs another key to activate the secondary function. For example, on a Acer keyboard SysRq is a secondary function of the Delete key and the Fn key is used to select the secondary function. So on this keyboard it would require holding down the Alt + Fn + Delete to activate the SysRq function.

Why Use R.E.I.S.U.B.?

• This method ensures a safe reboot because it syncs and unmounts your file systems properly, preventing data loss and minimizing the chance of file system corruption.
• It's much safer than simply holding down the power button, which can leave data in an inconsistent state.

Example of the Key Sequence in Action:

• The system freezes, and you cannot use the mouse or keyboard.
• Press and hold the Alt key and the SysRq key (Print Screen key).
• While holding these keys, type the sequence R, E, I, S, U, B one after the other.
• The system should reboot.

Important Notes:

• SysRq key: It is often labeled as Print Screen (PrtSc) on modern keyboards. On some laptops, you may need to press the Fn key along with Alt + SysRq.
• Patience: Each step of the sequence may take a few seconds to complete, especially on heavily loaded systems.
• Avoid Data Loss: If your system freezes frequently, consider investigating the root cause (e.g., hardware issues or misbehaving software), as R.E.I.S.U.B. should be a last resort.

Variations of Magic SysRq Commands:

You can also use individual SysRq commands without rebooting the system. For example:

• Alt + SysRq + S: Sync the disks.
• Alt + SysRq + U: Remount filesystems as read-only.
• Alt + SysRq + O: Shut down the system (instead of rebooting with B).

Summary:

R.E.I.S.U.B. is a life-saver in the Linux environments, allowing you to safely reboot a frozen system without damaging your files or operating system.

Just remember the key combination Alt + SysRq + R + E + I + S + U + B to execute the sequence correctly.

Just remember the phrase... Raising Elephants Is So Utterly Boring