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