mdw@git.distorted.org.uk Git - sgt/utils/blob - base64/base64.but

   1 \cfg{man-identity}{base64}{1}{2004-11-20}{Simon Tatham}{Simon Tatham}
   2
   3 \define{dash} \u2013{-}
   4
   5 \title Man page for \cw{base64}
   6
   7 \U NAME
   8
   9 \cw{base64} \dash stand-alone encoder and decoder for base64
  10
  11 \U SYNOPSIS
  12
  13 \c base64 [ -d ] [ filename ]
  14 \e bbbbbb   bb     iiiiiiii
  15 \c base64 -e [ -c width ] [ filename ]
  16 \e bbbbbb bb   bb iiiii     iiiiiiii
  17
  18 \U DESCRIPTION
  19
  20 \cw{base64} is a command-line utility for encoding and decoding the
  21 \q{base64} encoding.
  22
  23 This encoding, defined in
  24 \W{http://www.ietf.org/rfc/rfc2045.txt}{RFC 2045}, is primarily used
  25 to encode binary attachments in MIME e-mail, but is widely used in
  26 many other applications as well. For example, the \q{Content-MD5}
  27 mail header contains a small piece of base64; SSH private keys are
  28 generally stored as base64-encoded blobs; and so on.
  29
  30 Other utilities, such as \cw{munpack}, exist which will take an
  31 entire MIME-encoded message, identify the base64-encoded subparts,
  32 and decode them. However, these utilities will not help you if you
  33 need to inspect a Content-MD5 header or an SSH private key.
  34
  35 \cw{base64} is a very simple stand-alone encoder and decoder for the
  36 base64 format \e{alone}. It does not try to understand MIME headers
  37 or anything other than raw data.
  38
  39 \U OPTIONS
  40
  41 By default (if neither \cw{-d} or \cw{-e} is supplied), \cw{base64}
  42 operates in decode mode.
  43
  44 \dt \cw{-d}
  45
  46 \dd Places \cw{base64} into decode mode. In this mode, it will read
  47 from standard input or the supplied file name, ignore all characters
  48 that are not part of the base64 alphabet, decode the ones that are,
  49 and output the decoded data on standard output.
  50
  51 \dt \cw{-e}
  52
  53 \dd Places \cw{base64} into encode mode. In this mode, it will read
  54 binary data from standard input or the supplied file name, encode it
  55 as base64, and output the encoded data on standard output.
  56
  57 \dt \cw{-c} \e{width}
  58
  59 \dd If \cw{base64} is operating in encode mode, this controls the
  60 number of base64 characters output per line of the encoded file.
  61 Normally base64-reading applications do not care about this, so the
  62 default of 64 characters per line is perfectly adequate.
  63
  64 \lcont{
  65
  66 The special value 0 will prevent \cw{base64} from ever writing a
  67 line break in the middle of the data at all.
  68
  69 The base64 encoding converts between a group of three plaintext
  70 bytes and a group of four encoded bytes. \cw{base64} does not
  71 support breaking an encoded group across a line (although it can
  72 handle it as input if it receives it). Therefore, the \e{width}
  73 parameter passed to \cw{-c} must be a multiple of 4.
  74
  75 }
  76
  77 \U LICENCE
  78
  79 \cw{base64} is free software, distributed under the MIT licence.
  80 Type \cw{base64 --licence} to see the full licence text.
  81
  82 \versionid $Id$