REBOOT(8)REBOOT(8)NAME
reboot - UNIX bootstrapping procedures
SYNOPSIS
reboot [ -d ] [ -n ] [ -q ] [ -s ]
DESCRIPTION
UNIX is started by placing it at the beginning of physical memory and
transferring to the entry point. Since the system is not reenterable,
it is necessary to read it in from disk or tape each time it is to be
bootstrapped.
Rebooting a running system. When a UNIX is running and a reboot is
desired, shutdown(8) is normally used. If there are no users then
reboot can be used. Reboot 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 many users.
Options to reboot are:
-d option forces a memory dump to the swap area (see crash(8v))
before rebooting. This can be used if the system is in a funny
state that you would like to ``snapshot'' and analyze later.
-n option avoids the sync. It can be used if a disk or the proces‐
sor is on fire.
-q reboots quickly and ungracefully, without shutting down running
processes first.
-s option reboots to single user mode.
Reboot normally logs the reboot using syslog(8) and places a shutdown
record in the login accounting file (see utmp(5). These actions are
inhibited if the -n or -q options are present.
Power fail and crash recovery. Normally, the system will reboot itself
at power-up or after crashes. An automatic consistency check of the
file systems will be performed, and unless this fails, the system will
resume multi-user operations.
Cold starts. On an HP300, the boot procedure uses the boot rom to load
a boot program from an LIF format directory at the beginning of an
attached disk. The /usr/mdec directory contains a disk boot program
``bootrd'' which should be placed in a new pack automatically by
newfs(8) when the ``a'' partition file system on the pack is created.
This boot program finds the corresponding file on the given device
(vmunix by default), loads that file into memory, and starts the pro‐
gram at the entry address specified in the program header.
The boot program can be interrupted by typing `^C' (ctrl-C). This will
force the boot program to interactively prompt for a system to boot.
If not interrupted, it will boot from the device from which the boot
program itself was loaded.
The file specifications used for an interactive boot are of the form:
device(unit,minor)
where device is the type of the device to be searched, unit is 8 * the
hpib number plus the unit number of the disk or tape, and minor is the
disk partition or tape file number. Normal line editing characters can
be used when typing the file specification. Currently, ``rd'' is the
only valid device specifier.
For example, to boot from the `a' file system of unit 0 on HP-IB 2,
type “rd(16,0)vmunix” to the boot prompt. For tapes, the minor device
number gives a file offset.
In an emergency, the bootstrap methods described in the paper
``Installing 4.3bsd on the HP300'' can be used to boot from a distribu‐
tion tape.
FILES
/vmunix system code
/usr/mdec/bootrd LIF format boot block
/usr/mdec/installboot program to install boot blocks
SEE ALSOcrash(8V), fsck(8), halt(8), init(8), newfs(8), rc(8), shutdown(8),
syslogd(8)4.4 Berkeley Distribution June 29, 1990 REBOOT(8)