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Man Pages


Manual Reference Pages  -  NUMBER::BYTES::HUMAN (3)

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NAME

Number::Bytes::Human - Convert byte count to human readable format

CONTENTS

SYNOPSIS



  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); # -



DESCRIPTION

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.

  byte      B
  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:



  http://www.t1shopper.com/tools/calculate/



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:



  http://physics.nist.gov/cuu/Units/binary.html



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 %s\n", 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).

    OBJECTS

An alternative to the functional style of this module is the OO fashion. This is useful for avoiding the unnecessary parsing of the arguments over and over if you have to format lots of numbers



  for (@sizes) {
    my $fmt_size = format_bytes($_, @args);
    ...
  }



versus



  my $human = Number::Format::Bytes->new(@args);
  for (@sizes) {
    my $fmt_size = $human->format($_);
    ...
  }



for TODO [TODO] MAKE IT JUST A MATTER OF STYLE: memoize _parse_args() $seed == undef

    FUNCTIONS

<B>format_bytesB>


  $h_size = format_bytes($size, @options);



Turns a byte count (like 1230) to a readable format like ’1.3K’. You have a bunch of options to play with. See the section OPTIONS to know the details.

    METHODS

<B>newB>


  $h = Number::Bytes::Human->new(@options);



The constructor. For details on the arguments, see the section OPTIONS.

<B>formatB>


  $h_size = $h->format($size);



Turns a byte count (like 1230) to a readable format like ’1.3K’. The statements



  $h = Number::Bytes::Human->new(@options);
  $h_size = $h->format($size);



are equivalent to $h_size = format_bytes($size, @options), with only one pass for the option arguments.

<B>set_optionsB>


  $h->set_options(@options);



To alter the options of a Number::Bytes::Human object. See OPTIONS.

    OPTIONS

BASE


  block | base | block_size | bs => 1000 | 1024 | 1024000
  base_1024 | block_1024 | 1024 => 1
  base_1000 | block_1000 | 1000 => 1



The base to be used: 1024 (default), 1000 or 1024000.

Any other value throws an exception.

SUFFIXES


  suffixes => 1000 | 1024 | 1024000 | si_1000 | si_1024 | $arrayref



By default, the used suffixes stand for ’’, ’K’, ’M’, ... for base 1024 and ’’, ’k’, ’M’, ... for base 1000 (which are indeed the usual metric prefixes with implied unit as bytes, ’B’). For the weird 1024000 base, suffixes are ’’, ’M’, ’T’, etc.

ZERO


  zero => string | undef



The string 0 maps to (’0’ by default). If undef, the general case is used. The string may contain ’%S’ in which case the suffix for byte is used.



  format_bytes(0, zero => -) => -



METRIC SYSTEM


  si => 1



ROUND


  round_function => $coderef
  round_style => ceil | floor



TO_S
QUIET


  quiet => 1



Suppresses the warnings emitted. Currently, the only case is when the number is large than $base**(@suffixes+1).

    EXPORT

It is alright to import format_bytes, but nothing is exported by default.

DIAGNOSTICS



  "unknown round style $style";

  "invalid base: $block (should be 1024, 1000 or 1024000)";

  "round function ($args{round_function}) should be a code ref";

  "suffixes ($args{suffixes}) should be 1000, 1024, 1024000 or an array ref";

  "negative numbers are not allowed" (??)



TO DO

A function parse_bytes



  parse_bytes($str, $options)



which transforms ’1k’ to 1000, ’1K’ to 1024, ’1MB’ to 1E6, ’1M’ to 1024*1024, etc. (like gnu du).



  $str =~ /^\s*(\d*\.?\d*)\s*(\S+)/ # $num $suffix



SEE ALSO

lib/human.c and lib/human.h in GNU coreutils.

The _convert() solution by COG in Filesys::DiskUsage.

BUGS

Please report bugs via CPAN RT <http://rt.cpan.org/NoAuth/Bugs.html?Dist=Number-Bytes-Human> or <mailto://bug-Number-Bytes-Human@rt.cpan.org>. I will not be able to close the bug as BestPractical ignore my claims that I cannot log in, but I will answer anyway.

AUTHOR

Adriano R. Ferreira, <ferreira@cpan.org>

COPYRIGHT AND LICENSE

Copyright (C) 2005-2007 by Adriano R. Ferreira

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

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