However, note that this is rather rude if there are users on the system at
the time (who may be quite angry with you). The shutdown command
provides a method for changing runlevels in a way that treats users reasonably.
Similarly to the kill command's ability to send a variety of
signals to a process, shutdown can be used to halt, reboot, or
change to single-user mode. For example, to change to single-user mode in 5
minutes:
# shutdown 5
Broadcast message from root (pts/2) (Tue Jan 15 19:40:02 2002):
The system is going DOWN to maintenance mode in 5 minutes!
If you press control-c at this point, you can cancel the pending switch to
single-user mode. The message above would appear on all terminals on the
system, so users have a reasonable amount of time to save their work and log
off. (Some might argue whether or not 5 minutes is "reasonable.")