-.Pp
-.Tn UNIX
-is started by placing it in memory
-at location zero 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.
-.Pp
-.Sy Rebooting a running system .
-When a
-.Tn UNIX
-is running and a reboot is desired,
-.Xr shutdown 8
-is normally used.
-If there are no users then
-.Nm 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.
-.Pp
-Options to reboot are:
-.Bl -tag -width Ds
-.It Fl n
-option avoids the sync. It can be used if a disk or the processor
-is on fire.
-.It Fl q
-reboots quickly and ungracefully, without shutting down running
-processes first.
-.El
-.Pp
-.Nm Reboot
-normally logs the reboot using
-.Xr syslog 8
-and places a shutdown record in the login accounting file
-.Pa /var/log/wtmp.
-These actions are inhibited if the
-.Fl n
-or
-.Fl q
-options are present.
-.Pp