use strict;
use warnings;
use Data::Dumper;

my $file = "start<<<<part2>>>>middle<<<<part3>>>>end";
my @parts = split /<<<<(.+?)>>>>/, $file;
print Dumper \@parts;

##</code><code>##

$VAR1 = [
          'start',
          'part2',
          'middle',
          'part3',
          'end'
        ];