#initialize some variables
my $records; # No. of records
my $last;  # The last line
my $ini = 1; # set initial line
my $count = 1; # counter


for (my $count = 1; $count <= 20; $count++){
open (OLD, "< $old_file.txt") || die $!; # open file
# Now we need to split up the file into 20 files

open (NEW, "> $old_file$count.txt") || die $!; #open outputfile

while (<OLD>){
	if($. == $ini){
		chomp;
		$records = $_;
	}
}
close OLD;

$last = $ini + $records + 1;

open (OLD, "<$old_file.txt") || die $!; # I am more comfortable with re-opening the file like this
while (<OLD>){
	next unless $. >= $ini;
	print NEW $_;
	last if $. >= $last;
}
close OLD;
close NEW;
$ini = $last + 1;
}