Please read How do I post a question effectively? It sounds like you have the following:
  1. You have a 'Bayes' program running, writing output to a file
  2. After every N lines of output, you want to perform some processing
  3. This processing is to be done via a perl program
Is this right? If so, the easiest thing to do would be something like 
open BAYES, "tail -f bayes.out |" || die "could not open: $!";
while (<BAYES>) {
# read until you have enough to process
}

[download]
If this is not right, you will need to provide a better explanation...

In reply to Re: sampling with perl script by Illuminatus
in thread sampling with perl script by Anonymous Monk

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