You have a script that you need to run everytime your system boots? say, for example you need to dial up to connect to internet. Its very simple and straight forward:-
Write a script and add it to your /etc/init.d/ directory, say your script’s name is wvdial.sh
$ mv wvdial.sh /etc/init.d/
$ update-rc.d wvdial.sh defaults
that’s all… now boot your system and tada… no more typing in commands on the terminal after boot to do those daily bootup tasks!