shutdown(8) [osx man page]
SHUTDOWN(8) BSD System Manager's Manual SHUTDOWN(8) NAME
shutdown -- close down the system at a given time SYNOPSIS
shutdown [-] [-h [-u] | -r | -s | -k] [-o [-n]] time [warning-message ...] DESCRIPTION
The shutdown 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: -h The system is halted at the specified time. -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 If the -o is specified, prevent the file system cache from being flushed by passing -n option to halt(8) or reboot(8). This option should probably not be used. -o If -h or -r is specified, shutdown will execute halt(8) or reboot(8) instead of sending a signal to launchd(8). -r The system is rebooted at the specified time. -s The system is put to sleep at the specified time. -u 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 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, or yymmddhhmm, where the year, month, and day may be defaulted to the current system val- ues. 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 broadcast 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 starting at ten hours before shutdown, warning messages are displayed on the terminals of all users logged in. At shutdown time a message is written to the system log, containing the time of shutdown, the person who initiated the shutdown and the rea- son. Corresponding signal is then sent to launchd(8) to respectively halt, reboot or bring the system down to single-user state (depending on the above options). A scheduled shutdown can be canceled by killing the shutdown process (a SIGTERM should suffice). SIGTERM TO SIGKILL INTERVAL
Upon shutdown, all running processes are sent a SIGTERM followed by a SIGKILL. The SIGKILL will follow the SIGTERM by an intentionally inde- terminate period of time. Programs are expected to take only enough time to flush all dirty data and exit. Developers are encouraged to file a bug with the OS vendor, should they encounter an issue with this functionality. SEE ALSO
kill(1), login(1), wall(1), halt(8), launchd(8), reboot(8) BACKWARD COMPATIBILITY
The hours and minutes in the second time format may be separated by a colon (``:'') for backward compatibility. HISTORY
The shutdown utility appeared in 4.0BSD. BSD
December 11, 1998 BSD
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SHUTDOWN(8) BSD System Manager's Manual SHUTDOWN(8) 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 soft- ware 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 dis- abled 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
The shutdown command appeared in 4.0BSD. BSD
October 4, 2011 BSD