$str1='It is a guide to action which ensures that the military always obey the commands of the party.'; chomp($str1);
$str2='It is a guide to action that ensures that the military will forever heed Party commands is a guide.'; chomp($str2);

@arr1=split(/\s+/, $str1);
 $n=0;
for($i=0; $i<$#arr1;$i++) {
        $t1="$arr1[$i] $arr1[$i+1] $arr1[$i+2]";
        if($str2=~/$t1/) {
                print "$t1\12";
$n++;
        }
}
print "\n No of matching is : $n";

##</code><code>##

The output is:

It is a
is a guide
a guide to
guide to action
ensures that the
that the military
 
No of matching is : 6.