The Solaris O.S uses run levels to describe certain states of the overall m/c. An admin must be aware of the functionality provided at each level to ensure that the system runs smoothly
Run Level State Functionality
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0-------------------Power-down --------------Safe to turn off power to the system
1-------------------Admin Single user ------All available f.s with no user logins allowed. For admin tasks.
2-------------------Multiuser------------------Multiple users can access sys and f.s. except NFS and syslog.
3-------------------Multiuser w/NFS----------Multiple users with NFS resource sharing available.
4-------------------Alternative Multiuser---This level is currently unavailable.
5-------------------Power-down---------------Shutdown system and auto turn off system power.
6-------------------Reboot---------------------Shutdown and then reboot to multiuser state (def inittab file)
S,s-----------------Single-User---------------Single user mode with all f.s mounted and accessible.
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State the fn of the following files or dir and the relationships bet them: /etc/initab, /etc/init.d, /etc/rc# (where # falls in the range of 0 to 6, or S), or /etc/rc#.d
/etc/inittab = contains info about actions to occur at each system run level and is read by the init process.
The 3 items it defines are:
1. Default run level
2. A list of processes to start/restart and monitor
3. What to do when a new run level is started
The lines of the inittab file look like:
id:rstate:action:process
s6:6:wait:/sbin/rc6 >/dev/msglog 2<>/dev/msglog </dev/console
fw:0:wait:/sbin/uadmin 2 0 >/dev/msglog 2<>/dev/msglog </dev/console
sc:234:respawn:/usr/lib/saf/sac -t 300
co:234:respawn:/usr/lib/saf/ttymon -g -h -p "'uname -n ` console login: " -T sun -d /dev/console -l console -m ldterm, ttcompat
where
id is 4 character identifier,
rstate is the run level for the line to apply to
action is how the process will execute, and
process is what gets executed.
Some action keyworkds:
initdefault: specifies the default runlevel
sysinit: causes the line to execute and wait for completion before the file continues and before the console prompt appears
wait: also causes the line to execute before the script continues
resa\pawn: will start or restart processes as needed, or take no action if they don't exist
powerfail: executes the specified process if the powerfail signal is received
Message from scripts run from this file are saved to the /dev/msglog file.
