Your suggestion is valuable. I tried as you told...
rails server &
This script is working if i initiate as "/etc/init.d/webrick". But, it
doesnt start with system boot. (I provided 777 permission too...), I
dont know this will be permission issue for execution or some other issue.
You need to place a symbolic link in the directory of your current runlevel. It's something like /etc/rcX.d/. You get your current runlevel by executing `runlevel`. On Debian based system it's supposed to be 2. So you have to place the link in /etc/rc2.d.