System Administration Guide: Basic Administration

Procedurex86: How to Boot a System to Run Level S (Single-User Level)

Use this procedure to boot a system that is currently at run level 0 to run level S.

  1. If the system displays the Press any key to reboot prompt, press any key to reboot the system.

    You can also use the Reset button at this prompt. If the system is shut down, turn the system on with the power switch.

    The Current Boot Parameters menu is displayed after a few minutes.

  2. Type b -s to boot the system to run level S. Press Enter.

    If you do not make a selection within five seconds, the system is automatically booted to run level 3.

  3. Type the superuser password, if prompted.

  4. Verify that the system is at run level S.

    # who -r
       .       run-level S  Jul 19 14:37     S      0  3
  5. Perform the maintenance task that required the run level change to S.

  6. After you complete the system maintenance task, type Control-D to bring the system to the multiuser state.

Example 16–4 x86: Booting a System to Run Level S (Single-User Level)

Press any key to reboot.
Initializing system 
Please wait...

                     <<< Current Boot Parameters >>>
Boot path: /pci@0,0/pci-ide@7,1/ide@0/cmdk@0,0:a
Boot args:

Type    b [file-name] [boot-flags] <ENTER>     to boot with options
or      i <ENTER>                              to enter boot interpreter
or      <ENTER>                                to boot with defaults

                  <<< timeout in 5 seconds >>>

Select (b)oot or (i)nterpreter: b -s
SunOS Release 5.10 Version amd64-gate-2004-09-30 32-bit
Copyright 1983-2004 Sun Microsystems, Inc.  All rights reserved.
Use is subject to license terms.
DEBUG enabled
Booting to milestone "milestone/single-user:default".
Hostname: venus
NIS domain name is
Requesting System Maintenance Mode

Root password for system maintenance (control-d to bypass): xxxxxx
Entering System Maintenance Mode
# who -r
   .       run-level S  Jul 19 14:37     S      0  3
(Perform some maintenance task)
# ^D