use strict;
use warnings;

#slurp mode, read whole file in one variable
$/ = undef;
my $text = <DATA>;

if ($text =~ /xxxxx.*?\n.*?yyyyy.*?\n.*?zzzzz/) {
    print "match \n";
} else {
    print "no match \n";
}

__DATA__

xxxxx bla
yyyyy bla
bla zzzzz