You can use the following sub routine to extract particular lines from a file :

sub extract {
   my ($filename, $line_no)=@_;
   my $line;
   open (FILE, $filename) || die "$filename can't be opened $! "
   if ($line_no =~ /\D/) {
        while ($line=<FILE>) {
            if ($line =~ /$line_no/) {
                return $line;
            }
        }
   }
   else {
     foreach (1..$line_no) {
           $line = <FILE>;
        }
        return $line;
   }
}
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You have to pass the filename and the line number required. You can pass only one line no. required at a time. This can also be used to obtain a phrase from the file by passing the phrase to the sub routine.

An example:
$file = "example.txt";
$line_no_reqd = 4; 
$result = &imp($file,$line_no_reqd);
print $result;
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This example will fetch the contents in line no. 4 from the file, example.txt and print it.