The local boot commands file /etc/rc.d/rc.local
Create a file named /etc/init.d/local with the first lines (exactly!) inside plus the commands you would like to be executed:
#!/bin/sh
command 1
command 2
. . .
Then run as root:
chmod 755 /etc/init.d/local
update-rc.d local start 98 2 3 4 5 .
mkdir /etc/rc.d/
ln -s /etc/init.d/local /etc/rc.d/rc.local
Don't miss the . at the end of 2 3 4 5 .
All you put inside this newly created local boot commands file named /etc/rc.d/rc.local is executed at boot.
Ref: http://www.visoracle.com/download/debian/localboot.html