HOW-TO: magic reboot commands in Linux
Overview
"Magic reboot commands" are sometimes necessary if a system is especially unresponsive - such as when the root filesystem is read-only.
Examples
For example, say you have a system that has gone read-only, and you need to reboot it. But when you issue a “reboot” or “shutdown -r now”, the system responds like this:
# shutdown -r now -bash: /sbin/shutdown: Input/output error
In this case you can execute the following two “magic” commands:
echo 1 > /proc/sys/kernel/sysrq echo b > /proc/sysrq-trigger
