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 at run level 0 to run level S. The single-user level is used for performing system maintenance.


Note –

This procedure can be used for all GRUB implementations. However, the boot entries in the GRUB main menu vary, depending on the Solaris release you are running.


For a description of all the kernel options that you can specify in the GRUB menu at boot time, see x86: Modifying Boot Behavior by Editing the GRUB Menu at Boot Time.

  1. Reboot the system.


    # reboot
    

    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.

    When the boot sequence begins, the GRUB menu is displayed.

  2. When the GRUB main menu is displayed, type e to edit the GRUB menu.

  3. Depending on the release you are running, use the arrow keys to choose the kernel or kernel$ line.

    If you cannot use the arrow keys, use the caret key (^) key to scroll up and the letter v key to scroll down.

  4. Type e again to edit the boot entry.

    From here, you can add options and arguments to the kernel or kernel$ line.

  5. To boot the system in single-user mode, type -s at the end of the boot entry line. Then, press Return to go back to the previous screen.

    • To specify other boot behaviors, replace the -s option with the appropriate boot option.

      The following alternate boot behaviors can be specified in this manner.

      • Perform a reconfiguration boot.

      • Boot a 64-bit capable system in 32-bit mode.

      • Boot the system with the kernel debugger.

      • Redirect the console.

      For more information, see the boot(1M)man page.

  6. To boot the system in single-user mode, type b.

  7. When prompted, type the root password.


    Note –

    If you are running the OpenSolaris 2008.11 release, you need to also enter an account name before entering the root password. The account name can be root or any other privileged account, such as “jack” on the Live CD, or an account that you created during the installation.


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


    # who -r
    .       run-level S  Jun 13 11:07     S      0  0
  9. Perform the system maintenance task that required the run level change to S.

  10. After you complete the system maintenance task, reboot the system.


Example 12–10 x86: Booting a System in Single-User Mode


# reboot
Jul  2 14:30:01 pups reboot: initiated by root on /dev/console
syncing files...

Press <Ctrl><A> forPSCSISelect(TM) Utility!


GNU GRUB  version 0.95  (637K lower / 2096064K upper memory)

===================================================
Solaris 10 10/08 s10x_u6wos_03 X86 
Solaris failsafe

=====================================================
		Use the  and  keys to select which entry is highlighted.
		Press enter to boot the selected OS, 'e' to edit the
		commands before booting, or 'c' for a command-line.
=====================================================

GNU GRUB  version 0.95  (637K lower / 2096064K upper memory)

=====================================================
findroot (pool_rpool,0,a)
kernel$ /platform/i86pc/multiboot -B $ZFS-BOOTFS 
module /platform/i86pc/boot_archive
================================================
		Use the  and  keys to select which entry is highlighted.
		Press 'b' to boot, 'e' to edit the selected command in the
		boot sequence, 'c' for a command-line, 'o' to open a new line
		after ('O' for before) the selected line, 'd' to remove the
		selected line, or escape to go back to the main menu.

[ Minimal BASH-like line editing is supported.  For the first word, TAB
lists possible command completions.  Anywhere else TAB lists the possible
completions of a device/filename.  ESC at any time exits. ]

grub edit> kernel$ /platform/i86pc/multiboot -B $ZFS-BOOTFS -s

 GNU GRUB  version 0.95  (637K lower / 2096064K upper memory)

=======================================================
findroot (pool_rpool,0,a)
kernel$ /platform/i86pc/multiboot -B $ZFS-BOOTFS -s 
module /platform/i86pc/boot_archive
======================================
		Use the  and  keys to select which entry is highlighted.
		Press 'b' to boot, 'e' to edit the selected command in the
 	boot sequence, 'c' for a command-line, 'o' to open a new line
		after ('O' for before) the selected line, 'd' to remove the
   selected line, or escape to go back to the main menu.
.
.
.
SunOS Release 5.10
Copyright 1983-2008 Sun Microsystems, Inc.  All rights reserved.
Use is subject to license terms.
Booting to milestone "milestone/single-user:default".
Hostname: pups Requesting System Maintenance Mode SINGLE USER MODE
Root password for system maintenance (control-d to bypass):
single-user privilege assigned to /dev/console.
Entering System Maintenance Mode
Jul  2 14:41:48 su: 'su root' succeeded for root on /dev/console Sun Microsystems Inc.
# who -r
who -r    .       run-level S  Jul  2 14:39     S      0  0 #