System Administration Guide, Volume 1

Chapter 8 Run Levels and Boot Files (Tasks)

This chapter provides guidelines for shutting down and booting a system and information about run levels and boot files.

This is a list of the step-by-step instructions in this chapter.

This is a list of overview information in this chapter.

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 8-1 Solaris Run Levels

Run Level 

Init State 


Use This Level ... 

Power-down state 



To shut down the operating system so that it is safe to turn off power to the system.

s or S

Single-user state


To run as a single user with all file systems mounted and accessible.  

Administrative state 


To access all available file systems with user logins allowed.

Multiuser state 


For normal operations. Multiple users can access the system and the entire file system. All daemons are running except for the NFS server daemons.

Multiuser state with NFS resources shared


For normal operations with NFS resource-sharing available.

Alternative multiuser state 


This level is currently unavailable. 

Power-down state 


To shut down the operating system so that it is safe to turn off power to the system. If possible, automatically turn off power on systems that support this feature. 

Reboot state 


To shut down the system to run level 0, and then reboot to multiuser state (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 to determine a system's run level.

$ who -r

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

$ who -r
 .       run-level 3  Sep  1 14:45     3      0  S

run level 3

Identifies the current run level. 

Sep 1 14:45

Identifies the date of last run level change. 


Is the current run level. 


Identifies the number of times at this run level since the last reboot. 


Identifies the previous run level. 

The /etc/inittab File

When you boot the system or change run levels with the init or shutdown command, the init daemon starts processes by reading information from the /etc/inittab file. This file defines three important items for the init process:

Each entry in the /etc/inittab file has the following fields:


The following table describes the fields in an inittab entry.

Table 8-2 Fields in the inittab File




A unique identifier for the entry. 


A list of run levels to which this entry applies. 


How the process specified in the process field is to be run. Possible values include: initdefault, sysinit, boot, bootwait, wait, and respawn.


The command to execute. 

Example--Default inittab File

The following example shows an annotated default inittab file:

1 ap::sysinit:/sbin/autopush -f /etc/iu.ap
2 ap::sysinit:/sbin/soconfig -f /etc/sock2path
3 fs::sysinit:/sbin/rcS sysinit   >/dev/msglog 2<>/dev/msglog </dev/console
4 is:3:initdefault:
5 p3:s1234:powerfail:/usr/sbin/shutdown -y -i5 -g0 >/dev/msglog 2<>/dev/...
6 sS:s:wait:/sbin/rcS              >/dev/msglog 2<>/dev/msglog </dev/console
7 s0:0:wait:/sbin/rc0              >/dev/msglog 2<>/dev/msglog </dev/console
8 s1:1:respawn:/sbin/rc1           >/dev/msglog 2<>/dev/msglog </dev/console
9 s2:23:wait:/sbin/rc2             >/dev/msglog 2<>/dev/msglog </dev/console
10 s3:3:wait:/sbin/rc3             >/dev/msglog 2<>/dev/msglog </dev/console
11 s5:5:wait:/sbin/rc5             >/dev/msglog 2<>/dev/msglog </dev/console
12 s6:6:wait:/sbin/rc6             >/dev/msglog 2<>/dev/msglog </dev/console
13 fw:0:wait:/sbin/uadmin 2 0      >/dev/msglog 2<>/dev/msglog </dev/console
14 of:5:wait:/sbin/uadmin 2 6      >/dev/msglog 2<>/dev/msglog </dev/console
15 rb:6:wait:/sbin/uadmin 2 1      >/dev/msglog 2<>/dev/msglog </dev/console
16 sc:234:respawn:/usr/lib/saf/sac -t 300
17 co:234:respawn:/usr/lib/saf/ttymon -g -h -p "`uname -n` console login: " 
   -T terminal-type -d /dev/console -l console -m ldterm,ttcompat  
  1. Initializes STREAMS modules

  2. Configures socket transport providers

  3. Initializes file systems

  4. Defines default run level

  5. Describes a power fail shutdown

  6. Defines single-user mode

  7. Defines run level 0

  8. Defines run level 1

  9. Defines run level 2

  10. Defines run level 3

  11. Defines run level 5

  12. Defines run level 6

  13. Defines an unused level, firmware

  14. Defines an unused level, off

  15. Defines an unused level, reboot

  16. Initializes Service Access Controller

  17. Initializes console

What Happens When the System Is Brought to Run Level 3

  1. The init process is started and reads the /etc/default/init file to set any environment variables. By default, only the TIMEZONE variable is set.

  2. Then init reads the inittab file to do the following:

    1. Identify the initdefault entry, which defines the default run level (3).

    2. Execute any process entries that have sysinit in the action field so that any special initializations can take place before users login.

    3. Execute any process entries that have 3 in the rstate field, which matches the default run level, 3.

      See init(1M) for a detailed description of how the init process uses the inittab file.

      The following table describes the key words used for run level 3's action field.

      Table 8-3 Run Level 3 Action Key Word Descriptions

      Key Word 

      Starts the Specified Process ... 


      Only when the system receives a power fail signal. 


      And waits for its termination. 


      If it does not exist. If the process already exists, continue scanning the inittab file.

The following table describes the processes (or commands) executed at run level 3.

Table 8-4 Run Level 3 Command Descriptions

Command or Script Name 



Shuts down the system. The init process runs the shutdown command only if the system has received a powerfail signal.


Mounts and checks root (/), /usr, /var, and /var/adm file systems.


Starts the standard system processes, bringing the system up into run level 2 (multiuser mode). 


Starts NFS resource sharing for run level 3. 

/usr/lib/saf/sac -t 30

Starts the port monitors and network access for UUCP. This process is restarted if it fails. 

/usr/lib/saf/ttymon -g -h -p "`uname -n` console login: " -T terminal_type -d /dev/console -l console

Starts the ttymon process that monitors the console for login requests. This process is restarted if it fails.

The terminal_type on a SPARC based system is sun

The terminal_type on an IA based system is AT386

Run Control Scripts

The Solaris software environment provides a detailed series of run control (rc) scripts to control run level changes. Each run level has an associated rc script located in the /sbin directory:

For each rc script in the /sbin directory, there is a corresponding directory named /etc/rcn.d that contains scripts to perform various actions for that run level. For example, /etc/rc2.d contains files used to start and stop processes for run level 2.

# ls /etc/rc2.d
K07dmi             S70uucp            S75cron           S91afbinit
K07snmpdx          S71ldap.client     S75flashprom      S91ifbinit
K28nfs.server      S71rpc             S75savecore       S92volmgt
README             S71sysid.sys       S76nscd           S93cacheos.finish
S01MOUNTFSYS       S72autoinstall     S80PRESERVE       S94ncalogd
S05RMTMPFILES      S72inetsvc         S80lp             S95IIim
S20sysetup         S72slpd            S80spc            S95amiserv
S21perf            S73cachefs.daemon  S85power          S95ocfserv       S73nfs.client      S88sendmail       S99audit
S40llc2            S74autofs          S88utmpd          S99dtlogin
S47asppp           S74syslog          S89bdconfig
S69inet            S74xntpd           S90wbem

The /etc/rcn.d scripts are always run in ASCII sort order. The scripts have names of the form:


Files beginning with K are run to terminate (kill) a system process. Files beginning with S are run to start a system process.

Run control scripts are also located in the /etc/init.d directory. These files are linked to corresponding run control scripts in the /etc/rcn.d directories.

The actions of each run control script are summarized in Table 8-5.

Using a Run Control Script to Stop or Start Services

One advantage of having individual scripts for each run level is that you can run scripts in the /etc/init.d directory individually to turn off functionality without changing a system's run level.

How to Use a Run Control Script to Stop or Start a Service

  1. Become superuser.

  2. Turn off functionality.

    # /etc/init.d/filename stop
  3. Restart functionality.

    # /etc/init.d/filename start
  4. Use the pgrep command to verify whether the service has been stopped or started.

    # pgrep -f service

Example--Using a Run Control Script to Stop or Start a Service

Turn off NFS server functionality by typing:

# /etc/init.d/nfs.server stop
# pgrep -f nfs

Restart the NFS services by typing:

# /etc/init.d/nfs.server start
# pgrep -f nfs
# pgrep -f nfs -d, | xargs ps -fp
daemon   141     1 40   Jul 31 ?     0:00 /usr/lib/nfs/statd
root     143     1 80   Jul 31 ?     0:01 /usr/lib/nfs/lockd
root     245     1 34   Jul 31 ?     0:00 /usr/lib/nfs/nfsd -a 16
root     247     1 80   Jul 31 ?     0:02 /usr/lib/nfs/mountd

Adding a Run Control Script

If you want to add a run control script to start and stop a service, copy the script into the /etc/init.d directory and create links in the rcn.d directory you want the service to start and stop.

See the README file in each /etc/rcn.d directory for more information on naming run control scripts. The procedure below describes how to add a run control script.

How to Add a Run Control Script

  1. Become superuser.

  2. Add the script to the /etc/init.d directory.

    # cp filename /etc/init.d
    # chmod 0744 /etc/init.d/filename
    # chown root:sys /etc/init.d/filename
  3. Create links to the appropriate rcn.d directory.

    # cd /etc/init.d
    # ln filename /etc/rc2.d/Snnfilename
    # ln filename /etc/rcn.d/Knnfilename
  4. Use the ls command to verify that the script has links in the specified directories.

    # ls /etc/init.d/ /etc/rc2.d/ /etc/rcn.d/

Example--Adding a Run Control Script

# cp xyz /etc/init.d
# cd /etc/init.d
# ln xyz /etc/rc2.d/S100xyz
# ln xyz /etc/rc0.d/K100xyz
# ls /etc/init.d /etc/rc2.d /etc/rc0.d

Disabling a Run Control Script

Disable a run control script by renaming it with a dot (.) at the beginning of the new file name. Files that begin with a dot are not executed. If you copy a file by adding a suffix to it, both files will be run.

How to Disable a Run Control Script

  1. Become superuser.

  2. Rename the script by adding an underscore (_) to the beginning of the new file.

    # cd /etc/rcn.d
    # mv filename _filename
  3. Verify the script has been renamed.

    # ls
    # _filename

Example--Disabling a Run Control Script

The following example changes the S100datainit script name but saves the original script.

# cd /etc/rc2.d
# mv S100datainit _S100datainit

Run Control Script Summaries

Table 8-5 The /sbin/rc0 Script

Script Name 



Performs the following tasks: 


  • Stops system services and daemons

  • Terminates all running processes

  • Unmounts all file systems

Table 8-6 The /sbin/rc1 Script

Script Name 



Runs the /etc/rc1.d scripts to perform the following tasks:


  • Stops system services and daemons

  • Terminates all running processes

  • Unmounts all file systems

  • Brings the system up in single-user mode

Table 8-7 The /sbin/rc2 Script

Script Name 



Runs the /etc/rc2.d scripts to perform the following tasks:

  • Mounts all local file systems

  • Enables disk quotas if at least one file system was mounted with the quota option

  • Saves editor temporary files in /usr/preserve

  • Removes any files in the /tmp directory

  • Configures system accounting

  • Configures default router

  • Sets NIS domain and ifconfig netmask

  • Reboots the system from the installation media or a boot server if either /.PREINSTALL or /AUTOINSTALL exists

  • Starts inetd and rpcbind and named, if appropriate

  • Starts Kerberos client-side daemon, kerbd

  • Starts NIS daemons (ypbind) and NIS+ daemons (rpc.nisd), depending on whether the system is configured for NIS or NIS+, and whether the system is a client or a server

  • Starts keyserv, statd, lockd, xntpd, and utmpd

  • Mounts all NFS entries

  • Starts nscd (name service cache daemon)

  • Starts automount, cron, LP print service, sendmail, utmpd, and vold daemons

Note -

Many of the system services and applications that are started at run level 2 depend on what software is installed on the system.

Table 8-8 The /sbin/rc3 Script

Script Name 



Runs the /etc/rc3.d scripts to perform the following tasks:

  • Cleans up sharetab

  • Starts nfsd

  • Starts mountd

  • If the system is a boot server, starts rarpd, rpc.bootparamd, and rpld

  • Starts snmpdx (Solstice Enterprise AgentsTM process).

Table 8-9 The /sbin/rc5 and /sbin/rc6 Scripts

Script Name 


/sbin/rc5 and /sbin/rc6

Runs the /etc/rc0.d/K* scripts to perform the following tasks:

  • Kills all active processes

  • Unmounts the file systems


Table 8-10 The /sbin/rcS Script

Script Name 



Runs the /etc/rcS.d scripts to bring the system up to run level S. The following tasks are performed from these scripts:

  • Establishes a minimal network

  • Mounts /usr, if necessary

  • Sets the system name

  • Checks the root (/) and /usr file systems

  • Mounts pseudo file systems (/proc and /dev/fd)

  • Rebuilds the device entries for reconfiguration boots

  • Checks and mounts other file systems to be mounted in single-user mode