I normally write my IO scripts to take files on the command line, and output to STDOUT. (That makes the script a filter, and all kinds of wonderful proceed from there.)

So instead of opening an output file, and instead of looping over a list of files, do this:

while (<>) {
    do_something_here();
    print $blah if $accepted;
}
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Then you run it like so:

my_script blah*.log > my_output_file
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