Number::Bytes::Human is a Perl module that can convert byte count to human readable format.
use Number::Bytes::Human qw(format_bytes);
$size = format_bytes(0); # '0'
$size = format_bytes(2*1024); # '2.0K'
$size = format_bytes(1_234_890, bs => 1000); # '1.3M'
$size = format_bytes(1E9, bs => 1000); # '1.0G'
# the OO way
$human = Number::Bytes::Human->new(bs => 1000, si => 1);
$size = $human->format(1E7); # '10MB'
$human->set_options(zero => '-');
$size = $human->format(0); # '-'
THIS IS ALPHA SOFTWARE: THE DOCUMENTATION AND THE CODE WILL SUFFER CHANGES SOME DAY (THANKS, GOD!).
This module provides a formatter which turns byte counts to usual readable format, like '2.0K', '3.1G', '100B'. It was inspired in the -h option of Unix utilities like du, df and ls for "human-readable" output.
From the FreeBSD man page of df: http://www.freebsd.org/cgi/man.cgi?query=df
"Human-readable" output. Use unit suffixes: Byte, Kilobyte,
Megabyte, Gigabyte, Terabyte and Petabyte in order to reduce the
number of digits to four or fewer using base 2 for sizes.
kilobyte K = 2**10 B = 1024 B
megabyte M = 2**20 B = 1024 * 1024 B
gigabyte G = 2**30 B = 1024 * 1024 * 1024 B
terabyte T = 2**40 B = 1024 * 1024 * 1024 * 1024 B
petabyte P = 2**50 B = 1024 * 1024 * 1024 * 1024 * 1024 B
exabyte E = 2**60 B = 1024 * 1024 * 1024 * 1024 * 1024 * 1024 B
zettabyte Z = 2**70 B = 1024 * 1024 * 1024 * 1024 * 1024 * 1024 * 1024 B
yottabyte Y = 2**80 B = 1024 * 1024 * 1024 * 1024 * 1024 * 1024 * 1024 * 1024 B
I have found this link to be quite useful:
If you feel like a hard-drive manufacturer, you can start counting bytes by powers of 1000 (instead of the generous 1024). Just use bs => 1000.
But if you are a floppy disk manufacturer and want to start counting in units of 1024000 (for your "1.44 MB" disks)? Then use bs => 1_024_000.
If you feel like a purist academic, you can force the use of metric prefixes according to the Dec 1998 standard by the IEC. Never mind the units for base 1000 are ('B', 'kB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB') and, even worse, the ones for base 1024 are ('B', 'KiB', 'MiB', 'GiB', 'TiB', 'PiB', 'EiB', 'ZiB', 'YiB') with the horrible names: bytes, kibibytes, mebibytes, etc. All you have to do is to use si => 1. Ain't that beautiful the SI system? Read about it:
You can try a pure Perl "ls -lh"-inspired command with the one-liner, er, two-liner:
$ perl -MNumber::Bytes::Human=format_bytes
-e 'printf "%5s %sn", format_bytes(-s), $_ for @ARGV' *
Why to write such a module? Because if people can write such things in C, it can be written much easier in Perl and then reused, refactored, abused. And then, when it is much improved, some brave soul can port it back to C (if only for the warm feeling of painful programming).