down the system at a given time
provides an automated shutdown procedure
for superusers to nicely notify users when the system is shutting down, saving
them from system administrators, hackers, and gurus, who would otherwise not
bother with such niceties. When the shutdown
command is issued without options the system is placed in single user mode at
the indicated time after shutting down all system services.
The options are as follows:
- When used with -h,
-p, or -r causes
system to perform a dump. This option is useful for debugging system dump
procedures or capturing the state of a corrupted or misbehaving system.
See savecore(8) for
information on how to recover this dump.
- Create the file /fastboot so
that the file systems will not be checked by
fsck(8) during the next boot.
- The system is halted at the specified
- Kick everybody off. The -k
option does not actually halt the system, but leaves the system multi-user
with logins disabled (for all but superuser).
- When used with -h,
-p, or -r
prevents the normal sync(2)
before stopping the system.
- The system is powered down at the specified
time. The -p
flag is passed on to halt(8),
causing machines which support automatic power down to do so after
- shutdown execs
reboot(8) at the specified
- 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:
yymmddhhmm, where the year, month, and
day may be defaulted to the current system values. The first form brings
the system down in number minutes and the
second at the absolute time specified.
- Any other arguments comprise the warning message that is
broadcast to users currently logged into the system.
- If ‘-’ is
supplied as an option, the warning message is read from the standard
At intervals, becoming more frequent as apocalypse approaches and starting at
ten hours before shutdown, warning messages are displayed on the terminals of
all users logged in. Five minutes before shutdown, or immediately if shutdown
is in less than 5 minutes, logins are disabled by creating
and copying the warning message
there. If this file exists when a user attempts to log in,
prints its contents and
exits. The file is removed just before shutdown
At shutdown time a message is written in the system log, containing the time of
shutdown, who initiated the shutdown and the reason. A terminate signal is
then sent to init
to bring the system down to
single-user state (depending on above options). 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).
You can cancel a scheduled shutdown with the
command by killing the
- tells login not to let anyone log in
- run by rc(8)
before the system is shutdown
- tells rc(8) not
to run fsck(8) during the next
The hours and minutes in the second time format may be separated by a colon
(‘:’) for backward compatibility.
command appeared in