Manual Pages for UNIX Darwin command on man shutdown

SHUTDOWN(8) BSD System Manager's Manual SHUTDOWN(8)

NAME

sshhuuttddoowwnn - close down the system at a given time

SYNOPSIS

sshhuuttddoowwnn [-] [-hh [-uu] | -rr | -kk] [-oo [-nn]] time [warning-message ...]

DESCRIPTION

The sshhuuttddoowwnn utility 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. The following options are available:

-hh The system is halted at the specified time.

-rr The system is rebooted at the specified time.

-kk Kick everybody off. The -kk option does not actually halt the

system, but leaves the system multi-user with logins disabled

(for all but super-user).

-oo If -hh or -rr is specified, sshhuuttddoowwnn will execute halt(8) or

reboot(8) instead of sending signal to init(8).

-nn If the -oo is specified, prevent the file system cache from being

flushed by passing -nn option to halt(8) or reboot(8). This

option should probably not be used.

-uu The system is halted up until the point of removing system power,

but waits before removing power for 5 minutes so that an external UPS (uninterruptible power supply) can forcibly remove power.

This simulates a dirty shutdown to permit a later automatic power

on. OS X uses this mode automatically with supported UPSs in

emergency shutdowns.

time Time is the time at which sshhuuttddoowwnn 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, or 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.

warning-message

Any other arguments comprise the warning message that is broad-

cast to users currently logged into the system.

- If `-' is supplied as an option, the warning message is read from

the standard input.

At intervals, becoming more frequent as apocalypse approaches and start-

ing at ten hours before shutdown, warning messages are displayed on the

terminals of all users logged in. Five minutes before shutdown, or imme-

diately if shutdown is in less than 5 minutes, logins are disabled by

creating /var/run/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 sshhuuttddoowwnn exits.

At shutdown time a message is written to the system log, containing the

time of shutdown, the person who initiated the shutdown and the reason.

Corresponding signal is then sent to init(8) to respectively halt, reboot

or bring the system down to single-user state (depending on the above

options). The time of the shutdown and the warning message are placed in

/var/run/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).

A scheduled shutdown can be canceled by killing the sshhuuttddoowwnn process (a

SIGTERM should suffice). The /var/run/nologin file that sshhuuttddoowwnn created will be removed automatically. FILES /var/run/nologin tells login not to let anyone log in