shutdown -- Command

Shut down the COHERENT system
/etc/shutdown [ reboot | halt | single | powerfail ] time

shutdown shuts down the COHERENT system.  You must use this command to shut
COHERENT  down.   Failure  to shut  down  the  system  before rebooting  or
shutting off the computer could damage the COHERENT file system and destroy
data.

When you invoke shutdown, you  must specify the ``level'' shutdown, and the
time to shutdown.  The level must be one of the following:

reboot
     Bring down  the system, then reboot it  automatically.  Use this level
     if, for example, you are installing a new kernel.

halt Halt the system, but do not  reboot it or enter single-user mode.  Use
     this option when you intend to turn off your computer.

single
     Bring down the system to single-user mode.

powerfail
     Bring down the system as quickly as possible.  Normally, this level is
     invoked by  a daemon that has received information  of a power failure
     from your system's uninterruptable power supply (UPS).

time is the  interval, in minutes, from the time  you invoke the command to
the time that  shutdown shuts the system down.  Setting  time to zero shuts
down  the system  immediately.  Every  minute,  shutdown displays  on every
user's terminal the message

    System going down in N minutes!

where  N is  the number  of  minutes left  until shutdown.   When time  has
expired, shutdown displays the message

    System is going down now!

at which point users have ten  seconds to save their files and exit.  Users
who  have  turned  off system  messages  will  not,  of  course, see  these
messages.

After the  system has been halted,  you do not need  to type sync; shutdown
does that automatically.

If users have not logged off from the system when it comes time to shut the
system down, you will see the prompt:

    Some file systems remain mounted.  Proceed with shutdown ? [y]

If you type  `n', the shutdown will be aborted.   You should then make sure
that the  users have logged off, then invoke  /etc/shutdown again.  To lock
out new users from logging in while you are trying to shut the system down,
create the file /etc/nologin.  Note that this file is removed automatically
when you reboot your system.

If you  type `y', shutdown will  continue as before.  Users  will be thrown
off the system; any files they  might have had opened at that time will not
be updated.

See Also

commands,
nologin,
reboot

Notes

Only the superuser root can run shutdown.

shutdown can  be run from any terminal.  When  the system reboots, however,
control returns to the system console.

shutdown was written by Udo Munk (udo@umunk.GUN.de).

© 2012 by Stephen A. Ness