Is creating a regex, like the one discussed above, going to be the most efficient way?

It would be if you used Regexp::Assemble :) The code would look something like

use strict;
use Regexp::Assemble;

my $re = do {
    open IN, shift || 'file_of_IPs_sought' or die $!;
    my $guts = Regexp::Assemble->new->add(
        map {
            chomp;
            quotemeta($_)
        } <IN>
    )->as_string;
    close IN;
    qr/\b$guts\b/
};

open LOGFILE, shift || 'logfile' or die $!;
/$re/ and print while <LOGFILE>;
close LOGFILE;

# update: if this is a pipe...
/$re/ and print while <>;

[download]

The expression will probably turn out to be about the same size as the list of IPs. The more they cluster, the smaller the pattern will be. And 500 patterns will barely have Regexp::Assemble breaking a sweat.

- another intruder with the mooring in the heart of the Perl

In reply to Re: Efficient Way to Parse a Large Log File with a Large Regex (with Regexp::Assemble) by grinder
in thread Efficient Way to Parse a Large Log File with a Large Regex by Dru

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