Vidul Nikolaev Petrov

use strict;
use Getopt::Std;
use File::Basename;

getopts('scf:p:'); 

our($opt_s, $opt_c, $opt_f, $opt_p);

my $file = $opt_f;
my $size = $opt_p || 1;
my $len  = 1024;
my $c = 1;
my ($buf, $counter);

-f $file or usage();

if($opt_s){
    $size = 1024 * $size;

    open IN, "< $file" or die "cannot open_r $file $!";
    open OUT, "> $file.$c"  or die "cannot open_w $file $!";
    binmode IN;
    binmode OUT;

    while(read(IN, $buf, $len)){
        $counter++;
        if($counter > $size){
            $counter = 0;
            $c++;
            close OUT;
            open OUT, "> $file.$c"  or die "cannot open_w $file $!";
            binmode OUT;
        } 
        print OUT $buf
    }
} elsif($opt_c) {
    my @files = grep { -f and /^$file\.\d+$/ } glob '*';
    my $newfile = "splitter_$file";
    open OUT, ">> $newfile" or die "cannot open_w $file $!";
    binmode OUT;
    map { $_ =~ s/^$file\.// } @files;
    for(sort {$a<=>$b} @files ){
        open IN, "$file.$_" or die "cannot open_r $file $!";
        binmode IN;
        print OUT $_ while <IN>;
        close IN;
    }
} else {
    usage()
}

sub usage{
    my $pro = basename($0);
    print <<SQ;

$pro (-s|-c) -p piece size -f filename

    -s    split a file into pieces
    -c    collect a file from pieces
    -p     chunk size (defaults to 1MB)
    -f     file to be processed
SQ
    exit 1
}