Something

use warnings;
open LOG, "#rubik.IRCstorm.log" or die "Cannot open logfile";
my $file = "out";
my $num = "1";
my $fileout = $file . $num . ".txt";
open OUT, ">$fileout" or die "Cannot open output file";

my ($line, $count);
for $line (<LOG>) {
  print OUT $line;
  $count++;
  if ($count == 1000) { last; }
}
close OUT;
close LOG;


sub ChgOut {
  $num++;
  $fileout = $file . $num . ".txt";
  close OUT;
  open OUT, ">$fileout" or die "Error opening next output file";
}