Run Levels
A system's run level (also known as an init state) defines what services and resources are available to
users. A system can be in only one run level at a time.
The Solaris environment has eight run levels, which are described in
the following table. The default run level is specified in the /etc/inittab file as run level 3.
Table 11–1 Solaris Run Levels
Run Level
|
Init State
|
Type
|
Purpose
|
0
|
Power-down state
|
Power-down
|
To shut down the operating system so that it is safe to turn off power to
the system.
|
s or S
|
Single-user
state
|
Single-user
|
To run as a single user with some file systems mounted and accessible.
|
1
|
Administrative state
|
Single-user
|
To access all available file systems. User logins are disabled.
|
2
|
Multiuser state
|
Multiuser
|
For normal
operations. Multiple users can access the system and all file system. All
daemons are running except for the NFS server daemons.
|
3
|
Multiuser level with NFS resources shared
|
Multiuser
|
For normal operations with NFS resources shared. This is
the default run level for the Solaris environment.
|
4
|
Alternative multiuser state
|
|
Currently unavailable.
|
5
|
Power-down state
|
Power-down
|
To shut down
the operating system so that it is safe to turn off power to the system. If
possible, automatically turns off power on systems that support this feature.
|
6
|
Reboot state
|
Reboot
|
To shut down the
system to run level 0, and then reboot to multiuser level with NFS resources
shared (or whatever level is the default in the inittab
file).
|
How to Determine a System's Run Level
Display run level information by using the who -r
command.
Use the who -r command to determine a system's current
run level for any level, except run level 0.
Example—Determining a System's Run Level
This example displays information a system's current run level and information
about previous run levels.
$ who -r
. run-level 31 Dec 13 10:102 33 04 S5
$
|
-
Identifies the current run level
-
Identifies the date of last run level change
-
Also identifies the current run level
-
Identifies the number of times the system has been at this
run level since the last reboot
-
Identifies the previous run level