whats the line I have to insert in a cron.d file to run a file every 15 mins?

0,15,30,45 * * * * "command to run"

Oh, wait. I'm sorry. You are talking about a Cobalt RaQ. You can just stick the command you want to execute in a shell script and put it in "/etc/cron.quarter-hourly". E.g.:

#!/bin/sh
chmod 755 /home/site


That would chmod /home/site 755 every fifteen minutes.

As Vincent said, just place your shell scripts in /etc/cron.*

* = daily, quarter.daily, monthly .... check the different cron dirs.

works fine.