UNIX for Beginners Questions & Answers

When multiple files are involved I often do /tmp/$$-loggerdata, /tmp/$$-output2, and so forth. Don't forget to delete them when no longer needed or you'll have a mess.

This would be far better than just making exclusion, you'll be improving the usability of your program and removing a lot of potholes.

For locking across multiple servers with shared storage I would suggest that mkdir is better than a simple file creation because of the race condition that would leave. A mkdir will either work (return code zero, it did not exist and I created it) or fail (return code 1, it already exists or I cannot create it for some other reason)

The problem you have of cancelling or suspending a job is going to be a tough one to crack. If someone suspends their job for a long time and then re-enables it, you would expect that instance not to be getting confused by other requests, after all it was able to create the lock (however you did this)

You could, I suppose, disable interrupts with stty -isig (not sure if that's quite correct) and put in the trap suggested above, including the EXIT signal (so it cleans up when the script completes or aborts)

You would have to consider what happens if the server crashes and the lock cannot be cleaned up.

I know it sounds a daft question, but what is the conflict between the various servers running this at the same time? I just don't understand the need, so please help me and there may be a better way to organise this.



Kind regards,
Robin