NAME
shutdown - close down the system at a given time

SYNOPSIS
/usr/etc/shutdown time [ warning-message ... ]

DESCRIPTION
Shutdown provides an automated shutdown (quit) procedure which a
superuser can use to notify users nicely when the system is
shutting down, saving them from system administrators, hackers, and
gurus, who would otherwise not bother with niceties.

Time is the time at which shutdown will bring the system down and
may be the word now (indicating an immediate shutdown) or specify a
future time in one of two formats: +number and hour:min. The first
form brings the system down in number minutes and the second brings
the system down at the time of day indicated (as a 24-hour clock).

At intervals which get closer together as apocalypse approaches,
warning messages are displayed at the terminals of all users on the
system. Five minutes before shutdown, or immediately if shutdown
is in less than 5 minutes, logins are disabled by creating
/etc/nologin and writing a message there. If this file exists when
a user attempts to log in, login(1) prints its contents and exits.
The file is removed just before shutdown exits.

At shutdown time a message is written in the system log, containing
the time of shutdown, who ran shutdown and the reason. Shutdown
will exec reboot(8), to quit MachTen.

The time of the shutdown and the warning message are placed in
/etc/nologin and should be used to inform the users about when the
system will be back up and why it is going down (or anything else).

FILES
/etc/nologin tells login not to let anyone log in