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

NOTE: If your goal is to transition HP-UX to single-user mode from a higher run
level, do not use init s. This could leave processes running and disks mounted that
you do not want present.
Use the shutdown command with no parameters to transition to run level s, or to be
absolutely certain no undesirable processes or mounted file systems are present,
reboot the system to single-user mode by interrupting the boot process and using the
secondary boot loader (hpux.efi for Integrity servers or hpux for HP 9000 servers)
to override the default run level.
who -r The -r option of the who command displays the current system run level, the date
and time the current run level was entered, and three state fields representing the
current run level, how many times that run level was previously entered (since the
system was booted), and the previous run level (from which the current run level
was entered).
Example:
who -r
. run-level 3 Jun 27 06:22 3 1 4
This output indicates:
• The system is currently in run level 3.
• It entered the current run level on June 27th at 22 minutes after six in the morning.
• The current run level is (3) was previously entered one (1) time since the system
was last booted, and the current run level was entered from the previous run
level which was four (4).
Starting (Booting) HP-UX
HP-UX based systems go through the following sequential steps when you power them on or
reset them:
1. Hardware and/firmware-based routines on-board the processors and I/O cards perform
self-tests and initialize those items along with enough memory to continue the boot process.
They also locate and initialize communications with console display and keyboard devices,
and a boot device.
2. Pre-boot firmware/software routines then load and execute the HP-UX boot loader.
3. The HP-UX boot loader:
— Locates, opens, and reads the kernel file and copies the kernel into memory
— Initiates the HP-UX kernel
4. HP-UX goes through its initialization process and begins normal operation.
For complete details on the HP-UX boot process and its possible variations, see HP-UX System
Administrator’s Guide: Routine Management Tasks.
Stopping (Shutting Down) HP-UX
“READY . . . SET . . . GO!” As with the famous phrase, there is a definite order that you should
follow to shut down your system—or you may encounter problems.
When shutting down an HP-UX system:
Start-up and Shutdown 77