Ok. You need to create some datastore on your side. I would recommend some lite-weight database, like DBD::SQLite. You would then enter something for the downtime event. When you parse an uptime event, you will find the corresponding downtime event, delete it from your datastore, and send the full message to the Unix server. Something like:

1. Parse the syslog file.
2. For each event, do:
   1. If downtime event, enter event into local datastore.
   2. If uptime event, do:
      1. Find corresponding downtime event in local datastore.
      2. If it doesn't exist, error out.
      3. If it does, create string to send to Unix server.
      4. Send string to Unix server.
      5. Delete downtime event from local datastore.

The reason you want to delete the matched downtime event is you want to trap a duplicate message for the uptime event. (It sounds stupid, but there's very little cost associated and you trap a potential issue.)

As for how to do it ... knowing what you're trying to do is half the battle. Try your hand at coding up the above pseudo-code. Post here with any problems you run into.