The scripts in this directory are executed each time the system enters
this runlevel.

The scripts are all symbolic links whose targets are located in
/etc/init.d/ .

To disable a service in this runlevel, rename its script in this directory
so that the new name begins with a 'K' and a two-digit number, where the
number is the difference between the two-digit number following the 'S'
in its current name, and 100.  To re-enable the service, rename the script
back to its original name beginning with 'S'.

For a more information see /etc/init.d/README.