SHUTDOWN(8)    Linux System Administrator's Manual    SHUTDOWN(8)

NAME
       shutdown - bring the system down

SYNOPSIS
       /sbin/shutdown [-t sec] [-rkhncfF] 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 process-
       ing 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  sys-
       tem, runlevel 6 is used to reboot the system, and runlevel
       1 is used to put to system into a state where  administra-
       tive  tasks  can be performed; this is the default if nei-
       ther 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
       -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  mes-
              sages 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  dis-
              couraged, 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 mes-
              sage  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.

       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  filesys-
       tems.

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 autho-
       rized user is logged in on one of the virtual consoles. If
       shutdown  is  called from init(8), 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/shut-
       down.allow is one user name per line. Empty lines and com-
       ment lines (prefixed by a #) are allowed. Currently  there
       is a limit of 32 users in this file.

FILES
       /fastboot
       /etc/inittab
       /etc/init.d/halt
       /etc/init.d/reboot
       /etc/shutdown.allow

BUGS
       Not  really  a bug, but most users forget to give the time
       argument and are then puzzled by the error  message  shut-
       down  produces. The time argument is mandatory; in 90 per-
       cent of all cases this argument will be the word now.

AUTHOR
       Miquel van Smoorenburg, miquels@cistron.nl

SEE ALSO
       fsck(8), init(1), halt(8), reboot(8)

                           Nov 26, 1997                         1