but I don't know how to tell the regex that I don't want every single sentence that start with a keyword and end with the other, but just sentences that have three or four words between the first and the second.

To get that result, you could change
while ($text =~ / $key (.*)? $value /g)

to

while ($text =~ /\s$key\s+((?:\S+\s+){0,3}\S+)\s+$value\s/g)

This captures 1 to 4 words. (Do you really want space before $key and after $value?)

A few questions more.

• Can you match the same key and value more than once on the same string?
• Can more than one set of key/value be matched on the same string?

I ask because that is what your code is doing now in the section

while (my $text=<$testo>){
     for my $key (keys %hash){
       my $value = $hash{$key};
    while ($text =~ / $key (.*)? $value /g)  {
      
    $arrayris[$indice]=$1;
    $indice++;
      
    
    } 
      
    }  
}
[download]

If not, you would need to change the while loop, (testing the regular expression, not the file read),to an if statement.

Just a few questions.
Chris