in reply to extract trailer count one liner

Since it looks like your hit contains the letters TRL followed by one or more digits, you could express this as 
perl -ne 'print "$1\n" if /\[TRL(\d+)\]/;' <filename>

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This will also strip off the unwanted alpha chars.

#11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

In Section Seekers of Perl Wisdom