Script to imitate a Dead Man’s Switch

I want a script to put on my Macs that will ping a URL. If the site has a "O" then the script does not run, if the site has a "1" then it will delete files and folders that I tell it to. I want this script to run like CRON or at start up. I know that it could be circumvented by starting up from another disk, but I still think it is my best bet. Anyone who can offer any input or help? I would really appreciate it.