NAME

reboot − UNIX bootstrapping procedures

SYNOPSIS

/etc/reboot [ −n ] [ −q ]

DESCRIPTION

The UNIX operating system is started by placing it in memory at location zero and transferring to zero.  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 system is running and a reboot is desired, shutdown(8) is normally used.  If there are no users then /etc/reboot can be used.  Reboot performs a sync operation on the disks, and then a multi-user 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. 

OPTIONS

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

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

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

On both processors, the boot program finds the corresponding file on the given device, loads that file into memory location zero, and starts the program at the entry address specified in the program header (after clearing off the high bit of the specified entry address.)  Normal line editing characters can be used in specifying the pathname. 

For tapes, the minor device number gives a file offset. 

FILES

/vmunixsystem code
/bootsystem bootstrap

SEE ALSO

crash(8S), fsck(8), init(8), rc(8), shutdown(8), halt(8), newfs(8)

Sun Release 1.1  —  Last change: 28 October 1983