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Georg Brandl116aa622007-08-15 14:28:22 +00001:mod:`mailcap` --- Mailcap file handling
2========================================
3
4.. module:: mailcap
5 :synopsis: Mailcap file handling.
6
7
8
9Mailcap files are used to configure how MIME-aware applications such as mail
10readers and Web browsers react to files with different MIME types. (The name
11"mailcap" is derived from the phrase "mail capability".) For example, a mailcap
12file might contain a line like ``video/mpeg; xmpeg %s``. Then, if the user
13encounters an email message or Web document with the MIME type
14:mimetype:`video/mpeg`, ``%s`` will be replaced by a filename (usually one
15belonging to a temporary file) and the :program:`xmpeg` program can be
16automatically started to view the file.
17
18The mailcap format is documented in :rfc:`1524`, "A User Agent Configuration
19Mechanism For Multimedia Mail Format Information," but is not an Internet
20standard. However, mailcap files are supported on most Unix systems.
21
22
23.. function:: findmatch(caps, MIMEtype[, key[, filename[, plist]]])
24
25 Return a 2-tuple; the first element is a string containing the command line to
26 be executed (which can be passed to :func:`os.system`), and the second element
27 is the mailcap entry for a given MIME type. If no matching MIME type can be
28 found, ``(None, None)`` is returned.
29
30 *key* is the name of the field desired, which represents the type of activity to
31 be performed; the default value is 'view', since in the most common case you
32 simply want to view the body of the MIME-typed data. Other possible values
33 might be 'compose' and 'edit', if you wanted to create a new body of the given
34 MIME type or alter the existing body data. See :rfc:`1524` for a complete list
35 of these fields.
36
37 *filename* is the filename to be substituted for ``%s`` in the command line; the
38 default value is ``'/dev/null'`` which is almost certainly not what you want, so
39 usually you'll override it by specifying a filename.
40
41 *plist* can be a list containing named parameters; the default value is simply
42 an empty list. Each entry in the list must be a string containing the parameter
43 name, an equals sign (``'='``), and the parameter's value. Mailcap entries can
44 contain named parameters like ``%{foo}``, which will be replaced by the value
45 of the parameter named 'foo'. For example, if the command line ``showpartial
46 %{id} %{number} %{total}`` was in a mailcap file, and *plist* was set to
47 ``['id=1', 'number=2', 'total=3']``, the resulting command line would be
48 ``'showpartial 1 2 3'``.
49
50 In a mailcap file, the "test" field can optionally be specified to test some
51 external condition (such as the machine architecture, or the window system in
52 use) to determine whether or not the mailcap line applies. :func:`findmatch`
53 will automatically check such conditions and skip the entry if the check fails.
54
55
56.. function:: getcaps()
57
58 Returns a dictionary mapping MIME types to a list of mailcap file entries. This
59 dictionary must be passed to the :func:`findmatch` function. An entry is stored
60 as a list of dictionaries, but it shouldn't be necessary to know the details of
61 this representation.
62
63 The information is derived from all of the mailcap files found on the system.
64 Settings in the user's mailcap file :file:`$HOME/.mailcap` will override
65 settings in the system mailcap files :file:`/etc/mailcap`,
66 :file:`/usr/etc/mailcap`, and :file:`/usr/local/etc/mailcap`.
67
68An example usage::
69
70 >>> import mailcap
71 >>> d=mailcap.getcaps()
72 >>> mailcap.findmatch(d, 'video/mpeg', filename='/tmp/tmp1223')
73 ('xmpeg /tmp/tmp1223', {'view': 'xmpeg %s'})
74