#!/usr/bin/perl
use strict;
use warnings;
 
my ($message, $spacing);
if ($#ARGV >= 1) {
  $message = shift;
  $spacing = shift;
} else {
  die "Usage: els_find.pl message spacing files\n";
}
$spacing > 0 or die "Spacing must be greater than zero\n";
 
# Build a pattern that will recognize the message in regular
# text, ignoring punctuation and spacing.
my @letters = split //,$message;
my $pattern = join("(?:[^a-z]*[a-z]){$spacing}",@letters);
my $re = qr/($pattern)/i;
 
# Allow minimal wrapping across lines without having to slurp
# the whole file.
$/ = '';  # paragraph mode
while (<>) {
   chomp;
   if ($_ =~ $re) {
      print "Matched: *$1* at paragraph $. of file $ARGV\n";
   }
}