NAME

reboot − UNIX bootstrapping procedures

SYNOPSIS

/etc/reboot [ −dhnsq ]

DESCRIPTION

UNIX is started by placing it in memory at location zero and transferring to the start of the text segment.  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(1M) is normally used.  If there are no users then /etc/reboot can be used.  Reboot causes the disks to be synced, and then a full reboot (as described below) is 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. 

The reboot command can be used by super-user or by users that have the ACC_REBOOT and ACC_KILL bits set in their access vector. 

Options to reboot are:

−d forces a core dump prior to rebooting the system. 

−h Halts the processor rather than rebooting. 

−n option avoids the sync.  It can be used if a disk or the processor is on fire. 

−s Reboots to single user mode rather than to multi-user mode. 

−q reboots quickly and ungracefully, without shutting down running processes first. 

−w Mount the root file system as writable and don’t run fsck(1M) on the root file system prior to entering single user mode. The −w option implies the −s option. 

Power fail and crash recovery. Normally, the system will reboot itself at power-up or after crashes.  Provided the auto-restart is enabled through the console processor, an automatic consistency check of the file systems will be performed then and unless this fails the system will resume multi-user operations. 

Cold starts. Cold starts are performed from the system console processor. The exact commands used depend upon how much internal checking you wish the machine to perform and to what run level you wish to rise to (see boot(8) and init(1M)). 

For instance, a typical type of cold start would use the command

#> fb

This command will perform several CPU and memory tests, then boot the system according to the contents of the p23 register.  The command

#> fr/boot

will do the same thing, except it will skip the CPU and memory tests.  Use of this command is not recommended if you have powered off the machine to alter hardware, etc. The /etc/reboot command (when auto-restart is enabled) will perform the fb command upon restarting. 

See the CX/UX System Administration Manual for more information on booting procedures. 

FILES

/unixsystem code
/bootsystem bootstrap

SEE ALSO

fsck(1M), halt(1M), init(1M), newfs(1M), rc(1M), reboot(1M), shutdown(1M), boot(8), CX/UX System Administration Manual.

CX/UX Administrator’s Reference