use strict;
use warnings;

my $f=shift || die "File that your want to split\n";
my $chunk_size=shift || die "Chunk size\n";
my $dir=shift || die "Directory where the chunks are stored\n";
my $fsize=-s $f;
my $size=0;
my $buffer;
my $BUFFER_SIZE=4096;
my $nr_of_chunks=0;
my $nr=0;

if($chunk_size=~/(\d+)([mMgG])/) {
    my $numb=$1;
    my $tp=$2;
    SW: {
        ($tp eq "g" || $tp eq "G") && do {
            $numb*=1024*1024*1024;
            $size=$numb;
            last SW;
        };
        ($tp eq "m" || $tp eq "M") && do {
            $numb*=1024*1024;
            $size=$numb;
            last SW;
        };
    }
}
else {
    $size=$chunk_size;
}

open(F,$f) || die "OPEN : $!\n";
binmode(F);
if(! -e $dir) {
    mkdir($dir) || die "DIR : $!\n";
}
chdir($dir) || die "CHDIR : $!\n";

FILE:{
if(($fsize - $size)<=0) { 
    my $count=0;
    print "Creating file $nr\n";
    open(C,">$nr") || die "CREATE : $!\n";
    binmode(C);
        while($count != $fsize) {
        $count+=read(F,$buffer,$BUFFER_SIZE);
        print C $buffer;
    }
    close C;
    last FILE;
}
else {
    my $count=0;
    print "Creating file $nr\n";
    open(C,">$nr") || die "CREATE : $!\n";
    binmode(C);
        while($count != $size) {
        $count+=read(F,$buffer,$BUFFER_SIZE);
        print C $buffer;
    }
    close C;
    $fsize-=$size;
    $nr++;
    redo FILE;
}
}

print "Over & Out\n";

use strict;
use warnings;

my $dir=shift || die "Directory where the chunks are stored\n";
my $out=shift || die "Name under which we join the chunks\n";
my @files;
my $buffer;
opendir(D,$dir) || die "OPENDIR : $!\n";
@files=grep { /^\d+$/ } readdir(D);
closedir(D);
chdir($dir) || die "CHDIR : $!\n";
open(F,">../$out") || die "CREATE : $!\n";
binmode(F);
@files=sort { $a <=> $b } @files;
for(@files) {
    open(C,$_) || die "OPEN : $!\n";
        binmode(C);
    while(read(C,$buffer,4096)) {
        print F $buffer;
    }
    print "I joined chunk nr. $_\n";
    close C;
}
print "File $out is complete now\n";
close F;