[ Thanks to Mayank
for this link. ]
“System V method of initialization is one of the most widely
used across most Linux distributions. It definitely eases the
system administrators job. There’s a lot more than autoexec.bat and
config.sys here. We’ve written this article for novice users. It
explains the concept of runlevels, initialization scripts and the
significance of /etc/rc.d.”
“In the traditional BSD style of startup, there are only a few
initialization scripts, which are something like the autoexec.bat
and config.sys pair of DOS. Commands are executed and services are
loaded up sequentially as given in the scripts.”
“But the system administrator may want a more flexible and
convenient way of managing the system. There will be times when
certain services are not required. The BSD style of startup as
adopted by distributions like Slackware offered only a few system
states at the disposal of the administrator. A single user state
was provided for maintenance and there was a normal multi-user
state.”