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1 | \cfg{man-identity}{base64}{1}{2004-11-20}{Simon Tatham}{Simon Tatham} |
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2 | |
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3 | \title Man page for \cw{base64} |
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4 | |
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5 | \U NAME |
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6 | |
7 | \cw{base64} - stand-alone encoder and decoder for base64 |
8 | |
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9 | \U SYNOPSIS |
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10 | |
11 | \c base64 [ -d ] [ filename ] |
12 | \e bbbbbb bb iiiiiiii |
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13 | \c base64 -e [ -c width ] [ filename ] |
14 | \e bbbbbb bb bb iiiii iiiiiiii |
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15 | |
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16 | \U DESCRIPTION |
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17 | |
18 | \cw{base64} is a command-line utility for encoding and decoding the |
19 | \q{base64} encoding. |
20 | |
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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. |
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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 | |
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37 | \U OPTIONS |
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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 | |
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55 | \dt \cw{-c} \e{width} |
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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 |
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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. |
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72 | |
73 | } |
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74 | |
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75 | \U LICENCE |
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76 | |
77 | \cw{base64} is free software, distributed under the MIT licence. |
78 | Type \cw{base64 --licence} to see the full licence text. |
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79 | |
80 | \versionid $Id$ |