Update: Wanted to mention that this will not work if the pattern crosses 2 or more chunks.

The following uses MCE which does not read the entire file into memory. The example is based on fastsearch.pl from File::Map.

use 5.010;
use strict;
use warnings;

use MCE::Flow;

die "Not enough arguments given\n" if @ARGV < 2;

my $regex = shift;
$regex = qr/$regex/;

sub user_func {
   my ($mce, $slurp_ref, $chunk_id) = @_;

   if (my $match = ${ $slurp_ref } =~ $regex ? 1 : 0) {
      $mce->gather($match);
      $mce->abort;
   }
}

for my $filename (@ARGV) {
  my @match = mce_flow_f { use_slurpio => 1 }, \&user_func, $filename;
  say "File '$filename' does".( scalar @match ? "" : "n't" )." match";
}

[download]

Am providing a comparison in the event performance is a concern. Basically, MCE keeps up with File::Map.

$ time ./file_map.pl patternabc big_file
File 'big_file' doesn't match

real  0m0.327s
user  0m0.267s
sys   0m0.060s

$ time ./mce_slurp.pl patternabc big_file
File 'big_file' doesn't match

real  0m0.152s
user  0m0.263s
sys   0m0.118s

[download]

Also, see Re: Threads From Hell #2: How To Parse A Very Huge File.

In reply to Re: Possible to have regexes act on file directly (not in memory) by marioroy
in thread Possible to have regexes act on file directly (not in memory) by Nocturnus

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