NAME
shutdown —
close down the system at a
given time
SYNOPSIS
shutdown |
[-Ddfhknprvxz]
[-b
bootstr] time
[message ... |
-] |
DESCRIPTION
shutdown provides an automated shutdown procedure for
super-users 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.
Available friendlinesses:
-
-
- -b
bootstr
- The given bootstr is passed to
reboot(8) for the benefit of
those systems that can pass boot arguments to the firmware. Currently,
this only affects sun3 and sparc machines.
-
-
- -d
- shutdown will pass the
-d flag to
reboot(8) or
halt(8) to request a kernel
core dump. If neither the -h or -r
flags are specified, then -d also implies
-r.
-
-
- -f
- shutdown arranges, in the manner of
fastboot(8), for the file
systems not to be checked on reboot.
-
-
- -h
- The system is halted at the specified
time, using
halt(8).
-
-
- -k
- Kick everybody off. The -k option does
not actually halt the system, but leaves the system multi-user with logins
disabled (for all but super-user).
-
-
- -n
- Prevent the normal
sync(2) before stopping.
-
-
- -p
- The system is powered down at the specified
time, using
poweroff(8). If the
powerdown fails, or the system does not support software powerdown, the
system will simply halt instead.
-
-
- -r
- The system is rebooted at the specified
time, using
reboot(8).
-
-
- -v
- To enable verbose messages on the console, pass
-v to
reboot(8) or
halt(8).
-
-
- -x
- To enable debugging messages on the console, pass
-x to
reboot(8) or
halt(8).
-
-
- -z
- To silence some shutdown messages on the console, pass
-z to
reboot(8) or
halt(8).
-
-
- -D
- Prevents shutdown from detaching from the
tty with fork(2)/
exit(3).
-
-
- time
- Time is the time at which
shutdown will bring the system down and may be the word
now or a future time in one of two formats:
+number, or
[[[[[cc]yy]mm]dd]hh]mm, where the century, year,
month, day, and hour may be defaulted to the current system values. The
first form brings the system down number minutes
from the current time; the second brings the system down at the absolute
time specified. If the century is not specified, it defaults to 1900 for
years between 69 and 99, or 2000 for years between 0 and 68. A leading
zero in the “yy” value is not optional.
-
-
- message
...
- Any other arguments comprise the warning message that is
broadcast to users currently logged into the system.
-
-
- -
- If - is supplied as the only argument
after the time, the warning message is read from the standard input.
BEHAVIOR
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
/etc/nologin and copying the warning 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 initiated the shutdown, and the reason. Next a message is
printed announcing the start of the system shutdown hooks. Then the shutdown
hooks in
/etc/rc.shutdown are run, and a message is printed
indicating that they have completed. After a short delay,
shutdown runs
halt(8) or
reboot(8), or sends a terminate
signal to
init(8) to bring the
system down to single-user mode, depending on the choice of options.
The time of the shutdown and the warning message are placed in
/etc/nologin and should be used to tell the users why the
system is going down, when it will be back up, and to share any other
pertinent information.
FILES
- /etc/nologin
- tells login(1)
not to let anyone log in
- /fastboot
- tells rc(8) not
to run fsck(8) when
rebooting
- /etc/rc.shutdown
- System shutdown commands
SEE ALSO
login(1),
wall(1),
fastboot(8),
halt(8),
init(8),
poweroff(8),
reboot(8),
rescue(8)
BACKWARD COMPATIBILITY
The hours and minutes in the second time format may be separated by a colon
(``:'') for backward compatibility.
HISTORY
A
shutdown command was originally written by Ian Johnstone for
UNSW's modified
AT&T UNIX 6th Edn, modified, and
then incorporated in
4.1BSD.