Hello 1nickt,

I think the OP wanted all lines before the last instance of the TIMESTAMP match, including non-matching ones.

Yes, exactly, although since we are reading the file backwards, we should perhaps say: all lines from the first TIMESTAMP match (inclusive) to the end of the file.

Leaving aside the added line count, it seems to me that your code is logically identical to mine. Am I missing something?

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But in reading your post it occurs to me that there is a logic error in both of our approaches: what if the TIMESTAMP never has an exact match? The OP is, apparently, confident that there will always be a match, but a more robust design would allow for the possibility that there may not be:

my @log_final;

while (my $log_line = $log_bckwards->readline) {
    my $current_timestamp = extract_timestamp($log_line);
    last if compare_timestamps($current_timestamp, $TIMESTAMP) < 0;
    unshift @log_final, $log_line;
}
[download]

— with the implementation of extract_timestamp() and compare_timestamps() being left as the proverbial exercise for the reader. :-)

Hope that helps,