What is the diffe b/w init s and init S

UNIX Solaris
1

i did my research in finding the answer but couldn't find right one. Please give your inputs.

2

google finds this for me:
Sun init States

3

It looks like both means same getting into Single user mode. Then why did Sun has 2 diff run-levels for same purpose.

4

1 and s is the same... S is something other... read the link to the end.

5

Actually, "s" and "S" are the same, 1 is something slightly different.

6

init S:

will take you in the system maintenance mode, where you can use fsck on mounted file systems or to repair file systems...

init s

will take you in the single user mode, where you can unmount your whole file system and mount it on /a or /mnt and can make changes to filesystems...you can also use fsck here.

In short,
if you just need to do file system check, you can use "init S". and if you want to modify files, blocks, cylinders, you can use "init s"

Correct me if I am not....

7

use fsck on mounted filesystems ???, I hope not unless you remount them in read/only mode.

You are partially describing here the failsafe boot mode, not a run level.

Hmm, how do you modify blocks and cylinders in a file system context ?

I'm afraid you are confusing the failsafe boot mode, the administrative run level and the single user mode. Switching from multi-user to the "s" and "S" states is exactly the same operation* and put the OS in single user mode while "init 1" put the it in system administrator mode. Booting to failsafe mode cannot be achieved with the init command alone.