Pure Perl solutions are no doubt best, but one could read the smaller file into an array, add appropriate markers, e.g. escaped pipe symbols at both ends of each element, eliminate duplicates, and write the resulting array to a new file, and use fgrep -f, capturing its output by using backticks (`).

Being a brute-force-and-ignorance sort of guy, my first pure Perl attempt would be to read both files into arrays, generate a really, really long regex from the search criteria (smaller) file, and use grep. Given my Perl-mojo, this would not work, and I'd have to loop through the individual records of the larger file.

Information about American English usage here and here. Floating point issues? Please read this before posting. — emc

In reply to Re: Compare 2 files and create a new one if it matches by swampyankee
in thread Compare 2 files and create a new one if it matches by shawshankred

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