Thanks a lot Anonymous Monk.You rock!!!
This logic worked.Below is the final code :-

    open (FILE, '<', 'sample.txt') or die "Could not open sample.txt: 
+$!";
    open (FILE1, ">output1.txt") or die "Could not open sample.txt: $!
+";

    
    my @nums = <FILE>;  
my $start = "print from";
my $go = 0;
       my $sizeconf = scalar @nums;

for my $num ( @nums ){
    if ($num =~ /$start/)
    {
        
        $go = 1;
        
    }
   
    if($go){
       print FILE1 "$num";
    }
my $end = "closing";    
    if ($num =~ /$end/ && $num !~ /$start/)
    {
        $go = 0;
    }
}
[download]

The last point of "$num =~ /$end/ && $num !~ /$start/" because in my actual input file $start conatins the staring $end.

I will intergrate this logic with my tool and update you.