Add doc section about environment variables and defaults

[python-musicpd.git] / doc / source / use.rst

diff --git a/doc/source/use.rst b/doc/source/use.rst
index 28f94131c453a0532fc98a85918523b17b3c8687..f01fd398f0dc2937a2ca99b93393d64a4839f702 100644 (file)
--- a/doc/source/use.rst
+++ b/doc/source/use.rst
@@ -24,6 +24,28 @@ them), and the functions used to parse their responses see :ref:`commands`.
 
 See the `MPD protocol documentation`_ for more details.
 
+Environment variables
+---------------------
+
+The client honors the following environment variables:
+
+  * ``MPD_HOST`` MPD host (:abbr:`FQDN (fully qualified domain name)`, socket path or abstract socket) and password.
+
+    | To define a password set MPD_HOST to "`password@host`" (password only "`password@`")
+    | For abstract socket use "@" as prefix : "`@socket`" and then with a password  "`pass@@socket`"
+    | Regular unix socket are set with an absolute path: "`/run/mpd/socket`"
+  * ``MPD_PORT`` MPD port, relevant for TCP socket only, ie with :abbr:`FQDN (fully qualified domain name)` defined host
+  * ``MPD_TIMEOUT`` timeout for connecting to MPD and for waiting for MPD’s response in seconds
+  * ``XDG_RUNTIME_DIR`` path to look for potential socket: ``${XDG_RUNTIME_DIR}/mpd/socket``
+
+Defaults settings
+-----------------
+
+  * If ``MPD_HOST`` is not set, then look for a socket in ``${XDG_RUNTIME_DIR}/mpd/socket``
+  * If there is no socket use ``localhost``
+  * If ``MPD_PORT`` is not set, then use ``6600``
+  * If ``MPD_TIMEOUT`` is not set, then uses :py:obj:`musicpd.CONNECTION_TIMEOUT`
+
 Command lists
 -------------
 
@@ -107,14 +129,14 @@ Fetching album covers is possible with albumart, here is an example:
 
 .. code-block:: python
 
-    >>> fetched_cover_file = '/tmp/cover'
     >>> cli = musicpd.MPDClient()
     >>> cli.connect()
     >>> track = "Steve Reich/1978-Music for 18 Musicians"
-    >>> with open(fetched_cover_file, 'wb') as cover:
-    >>>     aart = cli.albumart(track, 0)
-    >>>     received = int(aart.get('binary'))
-    >>>     size = int(aart.get('size'))
+    >>> aart = cli.albumart(track, 0)
+    >>> received = int(aart.get('binary'))
+    >>> size = int(aart.get('size'))
+    >>> with open('/tmp/cover', 'wb') as cover:
+    >>>     # aart = {'size': 42, 'binary': 2051, data: bytes(...)}
     >>>     cover.write(aart.get('data'))
     >>>     while received < size:
     >>>         aart = cli.albumart(track, received)
@@ -124,6 +146,30 @@ Fetching album covers is possible with albumart, here is an example:
     >>>         print('something went wrong', file=sys.stderr)
     >>> cli.disconnect()
 
+A `CommandError` is raised if the album does not expose a cover.
+
+You can also use `readpicture` command to fetch embedded picture:
+
+.. code-block:: python
+
+    >>> cli = musicpd.MPDClient()
+    >>> cli.connect()
+    >>> track = 'muse/Amon Tobin/2011-ISAM/01-Amon Tobin - Journeyman.mp3'
+    >>> rpict = cli.readpicture(track, 0)
+    >>> if not rpict:
+    >>>     print('No embedded picture found', file=sys.stderr)
+    >>>     sys.exit(1)
+    >>> size = int(rpict['size'])
+    >>> done = int(rpict['binary'])
+    >>> with open('/tmp/cover', 'wb') as cover:
+    >>>     cover.write(rpict['data'])
+    >>>     while size > done:
+    >>>         rpict = cli.readpicture(track, done)
+    >>>         done += int(rpict['binary'])
+    >>>         print(f'writing {rpict["binary"]}, done {100*done/size:03.0f}%')
+    >>>         cover.write(rpict['data'])
+    >>> cli.disconnect()
+
 Refer to `MPD protocol documentation`_ for the meaning of `binary`, `size` and `data`.
 
 .. _MPD protocol documentation: http://www.musicpd.org/doc/protocol/