REBOOT(8) System Manager's Manual REBOOT(8)
reboot - stopping and restarting the system
/sbin/reboot [ -lqnhdarsfRD ]
/sbin/halt [ -lqndars ]
/sbin/fastboot [ -lqndarsRD ]
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.
Rebooting a running system: When the system is running and a reboot is desired, shutdown(8) is normally used to stop time sharing and put
the system into single user mode. If there are no users then /sbin/reboot can be used without shutting the system down first.
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.
Options to reboot are:
-l Don't try to tell syslogd(8) what's about to happen.
-q Reboot quickly and ungracefully, without shutting down running processes first.
-n Don't sync before rebooting. This can be used if a disk or the processor is on fire.
-h Don't reboot, simply halt the processor.
-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.
-a Have the system booter ask for the name of the system to be booted, rather than immediately booting the default system (/unix).
-r Mount the root file system as read only when the system reboots. This is not supported by the kernel in 2.11BSD.
-s Don't enter multi-user mode after system has rebooted - stay in single user mode.
-f Fast reboot. Omit the automatic file system consistency check when the system reboots and goes multi-user. This is accomplished by
passing a fast reboot flag on to the rebooting kernel. This currently prevents the use of -f flag in conjunction with the -h (halt)
-D Set the autoconfig(8) debug flag. This is normally not used unless one is debugging the autoconfig program.
-R Tells the kernel to use the compiled in root device. Normally the system uses the device from which it was booted as the
Reboot normally places a shutdown record in the login accounting file /usr/adm/wtmp. This is inhibited if the -q or -n options are
present. Note that the -f (fast reboot) and -n (don't sync) options are contradictory; the request for a fast reboot is ignored in this
Halt and fastboot are synonymous with ``reboot -h'' and ``reboot -f'', respectively.
Power fail and crash recovery: Normally, the system will reboot itself at power-up or after crashes if 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
autoconfig(8), sync(2), utmp(8), shutdown(8), syslogd(8)
3rd Berkeley Distribution May 24, 1996 REBOOT(8)