#!/usr/bin/perl

$/ = \10_000_000;   # according to IEEE, otherwise \10_485_760

open my $in, "<", $ARGV[0] or die $!;
binmode $in;
my $n = 1;
while (<$in>) {
    open my $out, ">", "outfile_".$n++ or die $!;
    binmode $out;
    print $out $_;
}

##</code><code>##

while (<>) {
    binmode(ARGV), seek(ARGV,0,0), next if $.==1;
    ...