HP-UX System Administrator's Guide: Overview HP-UX 11i v3 (B3921-90011, September 2010)

Example 3-4 Run Level Transition Examples
The following two examples show what happens during two typical situations:
Transition up
The file /etc/inittab contains an entry telling init that the initial
run level for the system during boot-up should be run level 3:
init:3:initdefault:
To reach run level 3, the system transitions:
From run level 0 (the halted state)
to run level 1 (running scripts pointed to by links in the /sbin/
rc1.d directory whose names begin with the letter S for example,
/sbin/rc1.d/S100localmount, /sbin/rc1.d/S520syncer,
and others).
to run level 2 (running scripts pointed to by links in the /sbin/
rc2.d directory whose names begin with the letter S for example,
/sbin/rc2.d/S500inetd, /sbin/rc2.d/S900samba, and
others).
and finally to run level 3 (running scripts pointed to by links in the
/sbin/rc3.d directory whose names begin with the letter S —
for example, /sbin/rc3.d/S823hpws_webmin, /sbin/rc3.d/
S823hpws_webproxy, and others).
Transition down If HP-UX is currently in run level 3 and an system administrator with
appropriate privileges executes the command:
/sbin/init 1
The system will transition:
From run level 3
to run level 2 (running scripts pointed to by links in the /sbin/
rc2.d directory whose names begin with the letter K — for
example, /sbin/rc2.d/K177hpws_tomcat, and others).
and finally to run level 1 (running scripts pointed to by links in the
/sbin/rc1.d directory whose names begin with the letter K —
for example, /sbin/rc1.d/K500inetd, and others).
Commands for Manipulating System Run Levels
The following commands can be used to set, change, and view HP-UX run levels:
init init is both a daemon and a command.
The init command interacts with the init daemon. You use the init command to
set or change run levels.
The init daemon, started at boot time spawns processes as defined in the /etc/
inittab file. These processes in turn control how HP-UX interacts with the outside
world (for example, which terminals to accept input from, and whether or not to
export local file systems via NFS for use by other servers).
76 Major Components of HP-UX