Your attempt at making a semaphore file is not having any effect. The race condition caused by reading and writing separately goes like this:
Process AProcess B
1readdata()
2readdata()
3writedata()
4writedata()
Process B's work is overwritten.

You should open the file once to read and write, flock it (blocking), read, process, and write. Close releases the lock.

To use a semaphore file, you should do a blocking sysopen with O_EXCL, and unlink the file when you're done. There's no need to use both methods.

I think you also have a problem with autovivifying globals in your subroutines, then expecting later lexicals to appear in their place. use warnings; use strict;.

After Compline,
Zaxo

In reply to Re: Disappearing File by Zaxo
in thread Disappearing File by Gorby

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