.\" Copyright (c) 1980 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	@(#)reboot.8	2.2 (2.11BSD) 1996/11/16
.\"
.TH REBOOT 8 "May 24, 1996"
.UC 2
.SH NAME
reboot \- stopping and restarting the system
.SH SYNOPSIS
.B /sbin/reboot
[
.B \-lqnhdarsfRD
]
.br
.B /sbin/halt
[
.B \-lqndars
]
.br
.B /sbin/fastboot
[
.B \-lqndarsRD
]
.SH DESCRIPTION
2.11BSD is started by placing it in memory at location zero and transferring to
its entry point.  Since the system is not reentrant, it is necessary to read
it in from disk or tape each time it is to be boot strapped.
.PP
.B "Rebooting a running system:"
When the system is running and a reboot is desired,
.IR shutdown (8)
is normally used to stop time sharing and put the system into single user
mode.  If there are no users then
.B /sbin/reboot
can be used without shutting the system down first.
.PP
Reboot normally causes the disks to be synced and allows the system to
perform other shutdown activities such as resynchronizing hardware
time-of-day clocks.  A multi-user reboot (as described below) is then
initiated.  This causes a system to be booted and an automatic disk check
to be performed.  If all this succeeds without incident, the system is then
brought up for multi-user operation.
.PP
Options to reboot are:
.TP
.B \-l
Don't try to tell
.IR syslogd (8)
what's about to happen.
.TP
.B \-q
Reboot quickly and ungracefully, without shutting down running processes
first.
.TP
.B \-n
Don't sync before rebooting.  This can be used if a disk or the processor
is on fire.
.TP
.B \-h
Don't reboot, simply halt the processor.
.TP
.B \-d
Dump memory onto the dump device, usually part of swap, before rebooting.
The dump is done in the same way as after a panic.
.TP
.B \-a
Have the system booter ask for the name of the system to be booted, rather
than immediately booting the default system (/unix).
.TP
.B \-r
Mount the root file system as
.I "read only"
when the system reboots.  This is not supported by the kernel in 2.11BSD.
.TP
.B \-s
Don't enter multi-user mode after system has rebooted \- stay in single
user mode.
.TP
.B \-f
Fast reboot.  Omit the automatic file system consistency check when the system
reboots and goes multi-user.  This is accomplished by passing a
.I fast reboot
flag on to the rebooting kernel.  This currently prevents the use of
.B \-f
flag in conjunction with the
.B \-h
(halt) flag.
.TP
.B \-D
Set the
.IR autoconfig (8)
debug flag.  This is normally not used unless one is debugging the
.I autoconfig
program.
.TP
.B \-R
Tells the kernel to use the compiled in root device.  Normally the system
uses the device from which it was booted as the root/swap/pipe/dump device.
.PP
.I Reboot
normally places a shutdown record in the login accounting file
/usr/adm/wtmp.  This is inhibited if the
.B \-q
or
.B \-n
options are present.
Note that the
.B \-f
(fast reboot) and
.B \-n
(don't sync)
options are contradictory; the request for a fast reboot is ignored in this
case.
.PP
.I Halt
and
.I fastboot
are synonymous with ``\fBreboot \-h\fP'' and ``\fBreboot \-f\fP'', respectively.
.PP
.B "Power fail and crash recovery:"
Normally, the system will reboot itself at power-up or after crashes
\fBif\fP the contents of low memory are intact.
An automatic consistency check of the file systems will be
performed, and unless this fails, the system will resume multi-user
operations.
.SH "SEE ALSO"
autoconfig(8),
sync(2),
utmp(8),
shutdown(8),
syslogd(8)