Home
Main website
Display Sidebar
Hide Ads
Recent Changes
View Source:
shutdown(8)
Edit
PageHistory
Diff
Info
LikePages
SHUTDOWN !!!SHUTDOWN NAME SYNOPSIS DESCRIPTION OPTIONS ACCESS CONTROL FILES NOTES AUTHOR SEE ALSO ---- !!NAME shutdown - bring the system down !!SYNOPSIS __/sbin/shutdown__ [[__-t__ ''sec''] [[__-arkhncfF__] ''time'' [[''warning-message''] !!DESCRIPTION __shutdown__ brings the system down in a secure way. All logged-in users are notified that the system is going down, and login(1) is blocked. It is possible to shut the system down immediately or after a specified delay. All processes are first notified that the system is going down by the signal SIGTERM . This gives programs like vi(1) the time to save the file being edited, mail and news processing programs a chance to exit cleanly, etc. __shutdown__ does its job by signalling the __init__ process, asking it to change the runlevel. Runlevel __0__ is used to halt the system, runlevel __6__ is used to reboot the system, and runlevel __1__ is used to put to system into a state where administrative tasks can be performed; this is the default if neither the ''-h'' or ''-r'' flag is given to __shutdown__. To see which actions are taken on halt or reboot see the appropriate entries for these runlevels in the file ''/etc/inittab''. !!OPTIONS __-a__ Use __/etc/shutdown.allow__. __-t__ ''sec'' Tell init(8) to wait ''sec'' seconds between sending processes the warning and the kill signal, before changing to another runlevel. __-k__ Don't really shutdown; only send the warning messages to everybody. __-r__ Reboot after shutdown. __-h__ Halt after shutdown. __-n__ [[DEPRECATED] Don't call init(8) to do the shutdown but do it ourself. The use of this option is discouraged, and its results are not always what you'd expect. __-f__ Skip fsck on reboot. __-F__ Force fsck on reboot. __-c__ Cancel an already running shutdown. With this option it is of course not possible to give the __time__ argument, but you can enter a explanatory message on the command line that will be sent to all users. ''time'' When to shutdown. ''warning-message'' Message to send to all users. The ''time'' argument can have different formats. First, it can be an absolute time in the format ''hh:mm'', in which ''hh'' is the hour (1 or 2 digits) and ''mm'' is the minute of the hour (in two digits). Second, it can be in the format __+__''m'', in which ''m'' is the number of minutes to wait. The word __now__ is an alias for __+0__. If shutdown is called with a delay, it creates the advisory file ''/etc/nologin'' which causes programs such as ''login(1)'' to not allow new user logins. Shutdown removes this file if it is stopped before it can signal init (i.e. it is cancelled or something goes wrong). It also removes it before calling init to change the runlevel. The __-f__ flag means `reboot fast'. This only creates an advisory file ''/fastboot'' which can be tested by the system when it comes up again. The boot rc file can test if this file is present, and decide not to run fsck(1) since the system has been shut down in the proper way. After that, the boot process should remove ''/fastboot''. The __-F__ flag means `force fsck'. This only creates an advisory file ''/forcefsck'' which can be tested by the system when it comes up again. The boot rc file can test if this file is present, and decide to run fsck(1) with a special `force' flag so that even properly unmounted filesystems get checked. After that, the boot process should remove ''/forcefsck''. The __-n__ flag causes __shutdown__ not to call __init__, but to kill all running processes itself. __shutdown__ will then turn off quota, accounting, and swapping and unmount all filesystems. !!ACCESS CONTROL __shutdown__ can be called from init(8) when the magic keys __CTRL-ALT-DEL__ are pressed, by creating an appropriate entry in ''/etc/inittab''. This means that everyone who has physical access to the console keyboard can shut the system down. To prevent this, __shutdown__ can check to see if an authorized user is logged in on one of the virtual consoles. If __shutdown__ is called with the __-a__ argument (add this to the invocation of shutdown in /etc/inittab), it checks to see if the file ''/etc/shutdown.allow'' is present. It then compares the login names in that file with the list of people that are logged in on a virtual console (from ''/var/run/utmp''). Only if one of those authorized users __or root__ is logged in, it will proceed. Otherwise it will write the message __shutdown: no authorized users logged in __to the (physical) system console. The format of ''/etc/shutdown.allow'' is one user name per line. Empty lines and comment lines (prefixed by a __#__) are allowed. Currently there is a limit of 32 users in this file. Note that if ''/etc/shutdown.allow'' is not present, the __-a__ argument is ignored. !!FILES /fastboot /etc/inittab /etc/init.d/halt /etc/init.d/reboot /etc/shutdown.allow !!NOTES A lot of users forget to give the ''time'' argument and are then puzzled by the error message __shutdown__ produces. The ''time'' argument is mandatory; in 90 percent of all cases this argument will be the word __now__. Init can only capture CTRL-ALT-DEL and start shutdown in console mode. If the system is running the X window System, the X server processes all key strokes. Some X11 environments make it possible to capture CTRL-ALT-DEL, but what exactly is done with that event depends on that environment. Shutdown wasn't designed to be run setuid. /etc/shutdown.allow is not used to find out who is executing shutdown, it ONLY checks who is currently logged in on (one of the) console(s). !!AUTHOR Miquel van Smoorenburg, miquels@cistron.nl !!SEE ALSO fsck(8), init(8), halt(8), poweroff(8), reboot(8) ----
7 pages link to
shutdown(8)
:
Man8s
halt(8)
last(1)
nologin(5)
pidof(8)
wall(1)
init(8)
This page is a man page (or other imported legacy content). We are unable to automatically determine the license status of this page.
