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python-3.7.4-docs-html/_sources/library/mailcap.rst.txt

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+:mod:`mailcap` --- Mailcap file handling
+========================================
+
+.. module:: mailcap
+   :synopsis: Mailcap file handling.
+
+**Source code:** :source:`Lib/mailcap.py`
+
+--------------
+
+Mailcap files are used to configure how MIME-aware applications such as mail
+readers and Web browsers react to files with different MIME types. (The name
+"mailcap" is derived from the phrase "mail capability".)  For example, a mailcap
+file might contain a line like ``video/mpeg; xmpeg %s``.  Then, if the user
+encounters an email message or Web document with the MIME type
+:mimetype:`video/mpeg`, ``%s`` will be replaced by a filename (usually one
+belonging to a temporary file) and the :program:`xmpeg` program can be
+automatically started to view the file.
+
+The mailcap format is documented in :rfc:`1524`, "A User Agent Configuration
+Mechanism For Multimedia Mail Format Information," but is not an Internet
+standard.  However, mailcap files are supported on most Unix systems.
+
+
+.. function:: findmatch(caps, MIMEtype, key='view', filename='/dev/null', plist=[])
+
+   Return a 2-tuple; the first element is a string containing the command line to
+   be executed (which can be passed to :func:`os.system`), and the second element
+   is the mailcap entry for a given MIME type.  If no matching MIME type can be
+   found, ``(None, None)`` is returned.
+
+   *key* is the name of the field desired, which represents the type of activity to
+   be performed; the default value is 'view', since in the  most common case you
+   simply want to view the body of the MIME-typed data.  Other possible values
+   might be 'compose' and 'edit', if you wanted to create a new body of the given
+   MIME type or alter the existing body data.  See :rfc:`1524` for a complete list
+   of these fields.
+
+   *filename* is the filename to be substituted for ``%s`` in the command line; the
+   default value is ``'/dev/null'`` which is almost certainly not what you want, so
+   usually you'll override it by specifying a filename.
+
+   *plist* can be a list containing named parameters; the default value is simply
+   an empty list.  Each entry in the list must be a string containing the parameter
+   name, an equals sign (``'='``), and the parameter's value.  Mailcap entries can
+   contain  named parameters like ``%{foo}``, which will be replaced by the value
+   of the parameter named 'foo'.  For example, if the command line ``showpartial
+   %{id} %{number} %{total}`` was in a mailcap file, and *plist* was set to
+   ``['id=1', 'number=2', 'total=3']``, the resulting command line would be
+   ``'showpartial 1 2 3'``.
+
+   In a mailcap file, the "test" field can optionally be specified to test some
+   external condition (such as the machine architecture, or the window system in
+   use) to determine whether or not the mailcap line applies.  :func:`findmatch`
+   will automatically check such conditions and skip the entry if the check fails.
+
+
+.. function:: getcaps()
+
+   Returns a dictionary mapping MIME types to a list of mailcap file entries. This
+   dictionary must be passed to the :func:`findmatch` function.  An entry is stored
+   as a list of dictionaries, but it shouldn't be necessary to know the details of
+   this representation.
+
+   The information is derived from all of the mailcap files found on the system.
+   Settings in the user's mailcap file :file:`$HOME/.mailcap` will override
+   settings in the system mailcap files :file:`/etc/mailcap`,
+   :file:`/usr/etc/mailcap`, and :file:`/usr/local/etc/mailcap`.
+
+An example usage::
+
+   >>> import mailcap
+   >>> d = mailcap.getcaps()
+   >>> mailcap.findmatch(d, 'video/mpeg', filename='tmp1223')
+   ('xmpeg tmp1223', {'view': 'xmpeg %s'})
+