shutdown.8

操作系统设计与实现源码

.TH SHUTDOWN 8
.SH NAME
shutdown \- graciously close the system down
.SH SYNOPSIS
.B shutdown
.RB [ \-hrRmk ]
.RB [ \-x
.IR code ]
.RI [ time-specification
.RI [ message ]]
.SH DESCRIPTION
.B Shutdown
is a program which allows a system operator to close down the system
in an nice way. 
.B 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 minutes),
.B shutdown
creates a file
.B /etc/nologin
to prevent new users from logging in.
.PP
.B Shutdown
keeps a logfile of shutdowns.  Every shutdown is registered in 
.BR /usr/adm/wtmp ,
if this file exists.  After these actions, a call is done to
.BR reboot (2)
which actually brings the system down.
.PP
.I Time-specification
may be something like
.BR 15:00 ,
.BR 15.00 ,
.BR +15 ,
or
.B now
for a shutdown at 3pm (twice), 15 minutes from now, or immediately.
.PP
The message may be used to describe why the system is going down, it may
also be typed on standard input with the
.B \-m
option.
.SH OPTIONS
.TP
.B \-h
This flag prevents the system from rebooting after the shutdown.  The
system can now be powered off.  This is the default.
.TP
.B \-r
This flag indicates that the system should reboot after shutting down.
.TP
.B \-R
Reboot the system by resetting it.  Normally the kernel will try to return
to the Boot Monitor.  With
.B \-R
the system will receive a hardware reset.
.TP
.BI \-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
.B "\-x 'boot hd0'"
as a very fast way to reboot "from the top."
.TP
.B \-m
Allows the operator to type a shutdown message on standard input, that will
be added to the messages displayed on all terminals.
.TP
.B \-k
This option gives the possibility of terminating an already started
shutdown.  This is only possible if shutdown time has not yet arrived.
.TP
.B \-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.)
.SH FILES
/usr/adm/wtmp, /etc/nologin, /usr/adm/authlog
.SH "SEE ALSO"
.BR reboot (2),
.BR wall (1),
.BR halt (8),
.BR boot (8).
.SH AUTHOR
Edvard Tuinder ([e-mail])