Hi samura,

If I were in your case, I'd be using 2 scripts.

Script 1 will be the one sending all those pings or "hellos" and will only be executed in one server which will serve as the checker.

Script 2 will be the "agent" who will send "acks" or acknowledgents or just simple ping backs to the server to express that the server is alive.

Its like a "I say hey you say ho" program.

Your problem can be solved with one script only but the problem with that is the checker may be able to ping or "see" the other machine but the other machine may not necessarily be able to "see" the server (due to firewalls or whatever reasons). Hence, the need for the "checker" and the "agent". But like I said earlier, just 1 script can suffice in some cases.

As for the sending of SMS, you'll have to have a machine that picks-up SMS messages and send it.

In my current company, we have an SMS server that parses XML files to be sent as SMS.

What we do is the server (checker), when needed to, ftps an XML file to the SMS server in an XML format. The SMS server, which just waits for available files, picks it up, parses it, then sends it.

The main script can be a cron job or an infinite script that uses a flat-file for reference of servers which it must ping (or ftp a file. The point is it must establish some means of communication with the other machine).

Now the 2nd script (if needed) may be a cron job or an infinite script that just waits for pings (or files from the server) then pings (or ftp's back) just to say "Yep, I'm still here"