#!/usr/bin/perl
use strict;

my $start_pattern = '<!-- start section-->';
my $end_pattern = '<!-- end section -->';
my @files_to_look_in = ("/path/to/files1.html", "/path/to/files2.html");

for(@files_to_look_in) {
    local $/;
    open(HTM_FILE, <$_) || die "Can't open file: $!";
    my $file = <HTM_FILE>;
    if ($file =~ /$start_pattern(.*)$end_pattern/s) {
        print "$1";
    }
}