used to count stream size. like tee, but not save stream to file.

szstat

#!/usr/bin/env perl

# head -c123456845 /dev/random | szstat >/dev/null

sub ps {
  my $n=shift @_;
  my @u=qw"B K M G T P E";
  my $i=0;
  while ($n>=1024 and $i<$#u) {
    $n /= 1024.0;
    $i += 1;
  }
  return sprintf("% 10.3f $u[$i]", $n);
}

$n = 2 * 1024; # copy per 2k

while ($n2 = read STDIN,$in,$n) {
  print $in; # output everything
  $c += $n2;
  print STDERR ("\r" . ps($c)) if ($c%(1024)==0);
}

print STDERR "\ntotal: ", ps($c), "\n";