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Test Your Knowledge in Computers #974
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Version 1.0 of the Linux kernel was released on 14 March 1994.
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shutdown(8) [bsd man page]

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

shutdown - close down the system at a given time SYNOPSIS
shutdown [ -k ] [ -r ] [ -h ] [ -f ] [ -n ] time [ warning-message ... ] DESCRIPTION
Shutdown provides an automated shutdown procedure which a super-user can use to notify users nicely when the system is shutting down, sav- ing them from system administrators, hackers, and gurus, who would otherwise not bother with niceties. 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 and hour:min. The first form brings the system down in number minutes and the second brings the system down at the time of day indicated (as a 24-hour clock). At intervals which get closer together as apocalypse approaches, warning messages are displayed at the terminals of all users on the sys- tem. Five minutes before shutdown, or immediately if shutdown is in less than 5 minutes, logins are disabled by creating /etc/nologin and writing a 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 ran shutdown and the reason. Then a termi- nate signal is sent to init to bring the system down to single-user state. Alternatively, if -r, -h, or -k was used, then shutdown will exec reboot(8), halt(8), or avoid shutting the system down (respectively). (If it isn't obvious, -k is to make people think the system is going down!) With the -f option, shutdown arranges, in the manner of fastboot(8), that when the system is rebooted the file systems will not be checked. The -n option prevents the normal sync(2) before stopping. 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). FILES
/etc/nologin tells login not to let anyone log in SEE ALSO
login(1), reboot(8), fastboot(8) BUGS
Only allows you to kill the system between now and 23:59 if you use the absolute time for shutdown. 4th Berkeley Distribution November 16, 1996 SHUTDOWN(8)

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

shutdown - graciously close the system down SYNOPSIS
shutdown [-hrRmk] [-x code] [time-specification [message]] DESCRIPTION
Shutdown is a program which allows a system operator to close down the system in an nice way. Shutdown informs the users why and when the system is going down. This warning is issued 10 minutes before shutdown time and every minute in the last 5 minutes. At this time (5 min- utes), shutdown creates a file /etc/nologin to prevent new users from logging in. Shutdown keeps a logfile of shutdowns. Every shutdown is registered in /usr/adm/wtmp, if this file exists. After these actions, a call is done to reboot(2) which actually brings the system down. Time-specification may be something like 15:00, 15.00, +15, or now for a shutdown at 3pm (twice), 15 minutes from now, or immediately. The message may be used to describe why the system is going down, it may also be typed on standard input with the -m option. OPTIONS
-h This flag prevents the system from rebooting after the shutdown. The system can now be powered off. This is the default. -r This flag indicates that the system should reboot after shutting down. -R Reboot the system by resetting it. Normally the kernel will try to return to the Boot Monitor. With -R the system will receive a hardware reset. -x code Halt the system and let the Monitor execute the given code as if typed at the monitor prompt. You can for instance use -x 'boot hd0' as a very fast way to reboot "from the top." -m Allows the operator to type a shutdown message on standard input, that will be added to the messages displayed on all terminals. -k This option gives the possibility of terminating an already started shutdown. This is only possible if shutdown time has not yet arrived. -C Check if the system crashed. This option is not used at shutdown time, but at reboot time. It tells if the file systems should be checked by testing if the last entry in the wtmp file is a shutdown entry. (A crude replacement for a file system clean flag.) FILES
/usr/adm/wtmp, /etc/nologin, /usr/adm/authlog SEE ALSO
reboot(2), wall(1), halt(8), boot(8). AUTHOR
Edvard Tuinder (v892231@si.hhs.NL) SHUTDOWN(8)

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