#!/usr/bin/perl

use strict;
use warnings;

use File::Find;

my $re = get_re();
my @dirs = qw/./;

find(\&wanted, @dirs);


sub wanted {
    return unless -f $_;

    open my $fh, "<", $_ or warn "Couldn't open $_: $!\n";

    while (<$fh>) {
        print "$File::Find::name:$_" if /$re/;
    }
}

sub get_re {
    my @words;

    while(<DATA>) {
        chomp;
        push @words, $_;
    }
    return join '|', map { "$_=" } @words;
}


__DATA__
sales
price
invoice