extract trailer count one liner

[dirtdog]

Hi Monks

I'm stuck trying to extract the Trailer count from a file that contains a Header and Trailer within brackets.

I have the following one-liner so far, but it doesn't quite get exactly what i need

perl -ne 'print "$1\n" if /\[(.*?)\]/;' <filename>

Sample input looks like this:

[HDR20140110230120]
--data content--
[TRL345]

The data content is swift data and is not surrounded by brackets so is not relevant for this example.

My expected result would be 345 in this example. Also, other samples of what the trailer record could be are:

 [TRL0] or [TRL25678]

It's a variable length count with no leading zeroes.

Any help would be greatly appreciated

thanks

[kennethk]

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>

This will also strip off the unwanted alpha chars.

[hdb]

If you are only looking for the digits, try

perl -ne 'print "$1\n" if /\[TRL(\d+)\]/;' <filename>

[Anonymous Monk]

And if the file is large, seek() relative to the end of file before you start to read. Say the known max-length of a trailer plus 50 bytes. Then read lines until you find one that matches the trailer regex.