Would this help?
perl -e '
$num1 = 5;
$num2= 10000;
open IN,"<","input_file.txt";
open OUT,">","output_file.txt";
print OUT <IN> for (1 .. $num1-1)
<IN> for ($num1 .. $num2);
undef $/ and print OUT <IN>;
close IN;
close OUT;
'
This removes any lines between 5 and 10000 inclusive. Change the numbers to fit your needs. Can't see an efficient way of doing it in situ, though (i.e. this approach will have to print to a different output file).
