jumdesumit:

Well, while you have several lines that match the pattern ([N01]{39}), none of the lines stop after the last [N01] match, they all have a semicolon and more text after them.

Try changing the line to not require that the line end immediately after that, like this:

    if ( $line =~ /([N01]{39})/ )
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or alternatively, specify that the string should be followed with a semicolon:

    if ( $line =~ /([N01]{39});/ )
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It would be helpful if you'd re-read perldoc perlre and verify that your expressions are saying what you really mean.

When I have a problem with a pattern, I usually do something akin to putting this at the start of the file:

use strict; use warnings;
while (my $line = <DATA>) {
    if ($line =~ /([N01]{39})$/) {
        print "line $.: <$1>\n";
    }
}
__DATA__
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And then run the file as a perl script. Then you can tweak your regex until you get what you're looking for. For example, when I ran it with the above bit of code on the front, I got this:

Roboticus@Waubli ~
$ perl pm1208422.pl

Roboticus@Waubli ~
$
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I then removed the '$' from your condition, re-ran it and got:

Roboticus@Waubli ~
$ perl pm1208422.pl
line 194: <NN0NNNNNNNNNNN0NNNNNNNNNNNNNNNNNNNNNNNN>
line 196: <NN0NNNNNNNNNNN1NNNNNNNNNNNNNNNNNNNNNNNN>
line 199: <NN0NNNNNNNNNNN1NNNNNNNNNNNNNNNNNNNNNNNN>
line 201: <NN0NNNNNNNNNNN0NNNNNNNNNNNNNNNNNNNNNNNN>
line 204: <NN0NNNNNNNNNNNNNNNNN0NNNNNNNNNNNNNNNNNN>
line 206: <NN0NNNNNNNNNNNNNNNNN1NNNNNNNNNNNNNNNNNN>
line 209: <NN0NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN0NN>
line 211: <NN00NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN1NN>
line 214: <NN0NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN0NNN>
line 216: <NN0NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN1NNN>
 . . . et cetera . . .
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Update: Fixed wording and formatting (code tags so square brackets don't linkify) in first sentence.

...roboticus

When your only tool is a hammer, all problems look like your thumb.