Booting an x86 Based System to a Specified State

The following procedures describe how to boot an x86 based system to a specified state, also known as run level booting.

Determining a System's Current Run Level

To determine a system's current run level, use the who -r command.

Example 2-1 Determining a System's Run Level

The output of the who -r command displays information about a system's current run level, as well as previous run levels.

$ who -r
 .    run-level 3  Dec 13 10:10  3  0 S
$

Output of `who` `-r` command	Description
`run-level 3`	Identifies the current run level
`Dec 13 10:10`	Identifies the date of last run level change
`3`	Also identifies the current run level
`0`	Identifies the number of times the system has been at this run level since the last reboot
`S`	Identifies the previous run level

Booting an x86 Based System to a Multiuser State (Run Level 3)

If a system is turned off, turning it on, or using the reboot command, starts the multiuser boot sequence.

Use the who -r command to verify that the system is brought to the specified run level. See Determining a System's Current Run Level.

How to Boot a System to a Multiuser State (Run Level 3)

Use this procedure to boot an x86 based system that is currently at run level 0 to run level 3.

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 main menu is displayed.
When the GRUB main menu is displayed, press Enter to boot the default OS instance.
If you do not select an entry within 10 seconds, the system automatically boots to run level 3.
The login prompt is displayed when the boot process has finished successfully.
Log in to the system.
```
hostname console login:
```

Verify that the system booted to run level 3.

$ who -r
   .       run-level 3  Mar  2 09:44     3      0  S

Booting an x86 Based System to a Single-User State (Run Level S)

Booting a system to a single-user state is used for system maintenance, such as backing up a file system or troubleshooting other system issues.

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

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 main menu is displayed.
When the GRUB main menu is displayed, type e to edit the GRUB menu.
Depending on the release you are running, use the arrow keys to select the kernel$ line.
If you cannot use the arrow keys, use the caret (^) key to scroll up and the letter v key to scroll down.
Type e again to edit the boot entry.
From here, you can add options and arguments to the kernel or kernel$ line.
To boot the system to a single-user state, type -s at the end of the boot entry line, then press Return to go back to the previous screen.
Note - 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 the system with the kernel debugger
- Redirect the console
For more information, see the boot(1M) man page.
To boot the system to a single-user state, type b.
When prompted, type the root password.

Verify that the system is at run level S.

# who -r
.       run-level S  Jun 13 11:07     S      0  0

Perform the system maintenance task that required the run level change to S.
After you complete the system maintenance task, reboot the system.

Booting an x86 Based System Interactively

Booting a system interactively is useful if you need to specify an alternate kernel or the /etc/system file during the boot process. Use the following procedure to boot a system interactively. Alternatively, you can resolve a problem with the /etc/system file by booting an alternative boot environment. See Initiating a Reboot of a System to a Newly Activated or Alternate Boot Environment.

How to Boot a System Interactively

Make backup copies of the /etc/system and the boot/solaris/filelist.ramdisk files, then add the /etc/system.bak file name to the /boot/solaris/filelist.ramdisk file. For example:
```
# cp /etc/system /etc/system.bak
# cp /boot/solaris/filelist.ramdisk /boot/solaris/filelist.ramdisk.orig
# echo "etc/system.bak" >> /boot/solaris/filelist.ramdisk
```
Update the boot archive.
```
# bootadm update-archive -v
```
Reboot the system.
```
# reboot
```
When the GRUB menu is displayed, select the OS that you want boot interactively, then type e.
Using the arrow keys, select the kernel$ line, then type e to edit the specified boot entry.
Type -a at the end of the line, then press Return.
Type b to boot the system interactively.
Respond the system prompts as follows:
1. Specify an alternate system file, then press Return.
```
Name of system file [etc/system]: /etc/system.bak
```
2. Specify the root file system, then press Return.
3. Specify the physical name of the root device, then press Return.
Pressing Return without providing any information accepts the system defaults.
Repair the damaged /etc/system file.
Reboot the system to run level 3.
```
# reboot
```

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