summaryrefslogtreecommitdiffstats
path: root/Doc/library/configparser.rst
blob: 6f0ae6ace82065de63f521600f9a47ad56919453 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
:mod:`configparser` --- Configuration file parser
=================================================

.. module:: configparser
   :synopsis: Configuration file parser.

.. moduleauthor:: Ken Manheimer <klm@zope.com>
.. moduleauthor:: Barry Warsaw <bwarsaw@python.org>
.. moduleauthor:: Eric S. Raymond <esr@thyrsus.com>
.. moduleauthor:: Łukasz Langa <lukasz@langa.pl>
.. sectionauthor:: Christopher G. Petrilli <petrilli@amber.org>
.. sectionauthor:: Łukasz Langa <lukasz@langa.pl>

.. index::
   pair: .ini; file
   pair: configuration; file
   single: ini file
   single: Windows ini file

This module provides the :class:`ConfigParser` class which implements a basic
configuration language which provides a structure similar to what's found in
Microsoft Windows INI files.  You can use this to write Python programs which
can be customized by end users easily.

.. note::

   This library does *not* interpret or write the value-type prefixes used in
   the Windows Registry extended version of INI syntax.

.. seealso::

   Module :mod:`shlex`
      Support for a creating Unix shell-like mini-languages which can be used
      as an alternate format for application configuration files.

   Module :mod:`json`
      The json module implements a subset of JavaScript syntax which can also
      be used for this purpose.


Quick Start
-----------

Let's take a very basic configuration file that looks like this:

.. code-block:: ini

   [DEFAULT]
   ServerAliveInterval = 45
   Compression = yes
   CompressionLevel = 9
   ForwardX11 = yes

   [bitbucket.org]
   User = hg

   [topsecret.server.com]
   Port = 50022
   ForwardX11 = no

The structure of INI files is described `in the following section
<#supported-ini-file-structure>`_.  Essentially, the file
consists of sections, each of which contains keys with values.
:mod:`configparser` classes can read and write such files.  Let's start by
creating the above configuration file programatically.

.. doctest::

   >>> import configparser
   >>> config = configparser.ConfigParser()
   >>> config['DEFAULT'] = {'ServerAliveInterval': '45',
   ...                      'Compression': 'yes',
   ...                      'CompressionLevel': '9'}
   >>> config['bitbucket.org'] = {}
   >>> config['bitbucket.org']['User'] = 'hg'
   >>> config['topsecret.server.com'] = {}
   >>> topsecret = config['topsecret.server.com']
   >>> topsecret['Port'] = '50022'     # mutates the parser
   >>> topsecret['ForwardX11'] = 'no'  # same here
   >>> config['DEFAULT']['ForwardX11'] = 'yes'
   >>> with open('example.ini', 'w') as configfile:
   ...   config.write(configfile)
   ...

As you can see, we can treat a config parser much like a dictionary.
There are differences, `outlined later <#mapping-protocol-access>`_, but
the behavior is very close to what you would expect from a dictionary.

Now that we have created and saved a configuration file, let's read it
back and explore the data it holds.

.. doctest::

   >>> import configparser
   >>> config = configparser.ConfigParser()
   >>> config.sections()
   []
   >>> config.read('example.ini')
   ['example.ini']
   >>> config.sections()
   ['bitbucket.org', 'topsecret.server.com']
   >>> 'bitbucket.org' in config
   True
   >>> 'bytebong.com' in config
   False
   >>> config['bitbucket.org']['User']
   'hg'
   >>> config['DEFAULT']['Compression']
   'yes'
   >>> topsecret = config['topsecret.server.com']
   >>> topsecret['ForwardX11']
   'no'
   >>> topsecret['Port']
   '50022'
   >>> for key in config['bitbucket.org']: print(key)
   ...
   user
   compressionlevel
   serveraliveinterval
   compression
   forwardx11
   >>> config['bitbucket.org']['ForwardX11']
   'yes'

As we can see above, the API is pretty straightforward.  The only bit of magic
involves the ``DEFAULT`` section which provides default values for all other
sections [1]_.  Note also that keys in sections are
case-insensitive and stored in lowercase [1]_.


Supported Datatypes
-------------------

Config parsers do not guess datatypes of values in configuration files, always
storing them internally as strings.  This means that if you need other
datatypes, you should convert on your own:

.. doctest::

   >>> int(topsecret['Port'])
   50022
   >>> float(topsecret['CompressionLevel'])
   9.0

Extracting Boolean values is not that simple, though.  Passing the value
to ``bool()`` would do no good since ``bool('False')`` is still
``True``.  This is why config parsers also provide :meth:`getboolean`.
This method is case-insensitive and recognizes Boolean values from
``'yes'``/``'no'``, ``'on'``/``'off'`` and ``'1'``/``'0'`` [1]_.
For example:

.. doctest::

   >>> topsecret.getboolean('ForwardX11')
   False
   >>> config['bitbucket.org'].getboolean('ForwardX11')
   True
   >>> config.getboolean('bitbucket.org', 'Compression')
   True

Apart from :meth:`getboolean`, config parsers also provide equivalent
:meth:`getint` and :meth:`getfloat` methods, but these are far less
useful since conversion using :func:`int` and :func:`float` is
sufficient for these types.


Fallback Values
---------------

As with a dictionary, you can use a section's :meth:`get` method to
provide fallback values:

.. doctest::

   >>> topsecret.get('Port')
   '50022'
   >>> topsecret.get('CompressionLevel')
   '9'
   >>> topsecret.get('Cipher')
   >>> topsecret.get('Cipher', '3des-cbc')
   '3des-cbc'

Please note that default values have precedence over fallback values.
For instance, in our example the ``'CompressionLevel'`` key was
specified only in the ``'DEFAULT'`` section.  If we try to get it from
the section ``'topsecret.server.com'``, we will always get the default,
even if we specify a fallback:

.. doctest::

   >>> topsecret.get('CompressionLevel', '3')
   '9'

One more thing to be aware of is that the parser-level :meth:`get` method
provides a custom, more complex interface, maintained for backwards
compatibility.  When using this method, a fallback value can be provided via
the ``fallback`` keyword-only argument:

.. doctest::

   >>> config.get('bitbucket.org', 'monster',
   ...            fallback='No such things as monsters')
   'No such things as monsters'

The same ``fallback`` argument can be used with the :meth:`getint`,
:meth:`getfloat` and :meth:`getboolean` methods, for example:

.. doctest::

   >>> 'BatchMode' in topsecret
   False
   >>> topsecret.getboolean('BatchMode', fallback=True)
   True
   >>> config['DEFAULT']['BatchMode'] = 'no'
   >>> topsecret.getboolean('BatchMode', fallback=True)
   False


Supported INI File Structure
----------------------------

A configuration file consists of sections, each led by a ``[section]`` header,
followed by key/value entries separated by a specific string (``=`` or ``:`` by
default [1]_).  By default, section names are case sensitive but keys are not
[1]_.  Leading and trailing whitespace is removed from keys and values.
Values can be omitted, in which case the key/value delimiter may also be left
out.  Values can also span multiple lines, as long as they are indented deeper
than the first line of the value.  Depending on the parser's mode, blank lines
may be treated as parts of multiline values or ignored.

Configuration files may include comments, prefixed by specific
characters (``#`` and ``;`` by default [1]_).  Comments may appear on
their own on an otherwise empty line, possibly indented. [1]_

For example:

.. code-block:: ini

   [Simple Values]
   key=value
   spaces in keys=allowed
   spaces in values=allowed as well
   spaces around the delimiter = obviously
   you can also use : to delimit keys from values

   [All Values Are Strings]
   values like this: 1000000
   or this: 3.14159265359
   are they treated as numbers? : no
   integers, floats and booleans are held as: strings
   can use the API to get converted values directly: true

   [Multiline Values]
   chorus: I'm a lumberjack, and I'm okay
       I sleep all night and I work all day

   [No Values]
   key_without_value
   empty string value here =

   [You can use comments]
   # like this
   ; or this

   # By default only in an empty line.
   # Inline comments can be harmful because they prevent users
   # from using the delimiting characters as parts of values.
   # That being said, this can be customized.

       [Sections Can Be Indented]
           can_values_be_as_well = True
           does_that_mean_anything_special = False
           purpose = formatting for readability
           multiline_values = are
               handled just fine as
               long as they are indented
               deeper than the first line
               of a value
           # Did I mention we can indent comments, too?


Interpolation of values
-----------------------

On top of the core functionality, :class:`ConfigParser` supports
interpolation.  This means values can be preprocessed before returning them
from ``get()`` calls.

.. class:: BasicInterpolation()

   The default implementation used by :class:`ConfigParser`.  It enables
   values to contain format strings which refer to other values in the same
   section, or values in the special default section [1]_.  Additional default
   values can be provided on initialization.

   For example:

   .. code-block:: ini

      [Paths]
      home_dir: /Users
      my_dir: %(home_dir)s/lumberjack
      my_pictures: %(my_dir)s/Pictures


   In the example above, :class:`ConfigParser` with *interpolation* set to
   ``BasicInterpolation()`` would resolve ``%(home_dir)s`` to the value of
   ``home_dir`` (``/Users`` in this case).  ``%(my_dir)s`` in effect would
   resolve to ``/Users/lumberjack``.  All interpolations are done on demand so
   keys used in the chain of references do not have to be specified in any
   specific order in the configuration file.

   With ``interpolation`` set to ``None``, the parser would simply return
   ``%(my_dir)s/Pictures`` as the value of ``my_pictures`` and
   ``%(home_dir)s/lumberjack`` as the value of ``my_dir``.

.. class:: ExtendedInterpolation()

   An alternative handler for interpolation which implements a more advanced
   syntax, used for instance in ``zc.buildout``. Extended interpolation is
   using ``${section:option}`` to denote a value from a foreign section.
   Interpolation can span multiple levels. For convenience, if the ``section:``
   part is omitted, interpolation defaults to the current section (and possibly
   the default values from the special section).

   For example, the configuration specified above with basic interpolation,
   would look like this with extended interpolation:

   .. code-block:: ini

      [Paths]
      home_dir: /Users
      my_dir: ${home_dir}/lumberjack
      my_pictures: ${my_dir}/Pictures

   Values from other sections can be fetched as well:

   .. code-block:: ini

      [Common]
      home_dir: /Users
      library_dir: /Library
      system_dir: /System
      macports_dir: /opt/local

      [Frameworks]
      Python: 3.2
      path: ${Common:system_dir}/Library/Frameworks/

      [Arthur]
      nickname: Two Sheds
      last_name: Jackson
      my_dir: ${Common:home_dir}/twosheds
      my_pictures: ${my_dir}/Pictures
      python_dir: ${Frameworks:path}/Python/Versions/${Frameworks:Python}

Mapping Protocol Access
-----------------------

.. versionadded:: 3.2

Mapping protocol access is a generic name for functionality that enables using
custom objects as if they were dictionaries.  In case of :mod:`configparser`,
the mapping interface implementation is using the
``parser['section']['option']`` notation.

``parser['section']`` in particular returns a proxy for the section's data in
the parser.  This means that the values are not copied but they are taken from
the original parser on demand.  What's even more important is that when values
are changed on a section proxy, they are actually mutated in the original
parser.

:mod:`configparser` objects behave as close to actual dictionaries as possible.
The mapping interface is complete and adheres to the ``MutableMapping`` ABC.
However, there are a few differences that should be taken into account:

* By default, all keys in sections are accessible in a case-insensitive manner
  [1]_.  E.g. ``for option in parser["section"]`` yields only ``optionxform``'ed
  option key names.  This means lowercased keys by default.  At the same time,
  for a section that holds the key ``'a'``, both expressions return ``True``::

     "a" in parser["section"]
     "A" in parser["section"]

* All sections include ``DEFAULTSECT`` values as well which means that
  ``.clear()`` on a section may not leave the section visibly empty.  This is
  because default values cannot be deleted from the section (because technically
  they are not there).  If they are overriden in the section, deleting causes
  the default value to be visible again.  Trying to delete a default value
  causes a ``KeyError``.

* Trying to delete the ``DEFAULTSECT`` raises ``ValueError``.

* ``parser.get(section, option, **kwargs)`` - the second argument is **not**
  a fallback value. Note however that the section-level ``get()`` methods are
  compatible both with the mapping protocol and the classic configparser API.

* ``parser.items()`` is compatible with the mapping protocol (returns a list of
  *section_name*, *section_proxy* pairs including the DEFAULTSECT).  However,
  this method can also be invoked with arguments: ``parser.items(section, raw,
  vars)``. The latter call returns a list of *option*, *value* pairs for
  a specified ``section``, with all interpolations expanded (unless
  ``raw=True`` is provided).

The mapping protocol is implemented on top of the existing legacy API so that
subclasses overriding the original interface still should have mappings working
as expected.


Customizing Parser Behaviour
----------------------------

There are nearly as many INI format variants as there are applications using it.
:mod:`configparser` goes a long way to provide support for the largest sensible
set of INI styles available.  The default functionality is mainly dictated by
historical background and it's very likely that you will want to customize some
of the features.

The most common way to change the way a specific config parser works is to use
the :meth:`__init__` options:

* *defaults*, default value: ``None``

  This option accepts a dictionary of key-value pairs which will be initially
  put in the ``DEFAULT`` section.  This makes for an elegant way to support
  concise configuration files that don't specify values which are the same as
  the documented default.

  Hint: if you want to specify default values for a specific section, use
  :meth:`read_dict` before you read the actual file.

* *dict_type*, default value: :class:`collections.OrderedDict`

  This option has a major impact on how the mapping protocol will behave and how
  the written configuration files look.  With the default ordered
  dictionary, every section is stored in the order they were added to the
  parser.  Same goes for options within sections.

  An alternative dictionary type can be used for example to sort sections and
  options on write-back.  You can also use a regular dictionary for performance
  reasons.

  Please note: there are ways to add a set of key-value pairs in a single
  operation.  When you use a regular dictionary in those operations, the order
  of the keys may be random.  For example:

  .. doctest::

     >>> parser = configparser.ConfigParser()
     >>> parser.read_dict({'section1': {'key1': 'value1',
     ...                                'key2': 'value2',
     ...                                'key3': 'value3'},
     ...                   'section2': {'keyA': 'valueA',
     ...                                'keyB': 'valueB',
     ...                                'keyC': 'valueC'},
     ...                   'section3': {'foo': 'x',
     ...                                'bar': 'y',
     ...                                'baz': 'z'}
     ... })
     >>> parser.sections()
     ['section3', 'section2', 'section1']
     >>> [option for option in parser['section3']]
     ['baz', 'foo', 'bar']

  In these operations you need to use an ordered dictionary as well:

  .. doctest::

     >>> from collections import OrderedDict
     >>> parser = configparser.ConfigParser()
     >>> parser.read_dict(
     ...   OrderedDict((
     ...     ('s1',
     ...      OrderedDict((
     ...        ('1', '2'),
     ...        ('3', '4'),
     ...        ('5', '6'),
     ...      ))
     ...     ),
     ...     ('s2',
     ...      OrderedDict((
     ...        ('a', 'b'),
     ...        ('c', 'd'),
     ...        ('e', 'f'),
     ...      ))
     ...     ),
     ...   ))
     ... )
     >>> parser.sections()
     ['s1', 's2']
     >>> [option for option in parser['s1']]
     ['1', '3', '5']
     >>> [option for option in parser['s2'].values()]
     ['b', 'd', 'f']

* *allow_no_value*, default value: ``False``

  Some configuration files are known to include settings without values, but
  which otherwise conform to the syntax supported by :mod:`configparser`.  The
  *allow_no_value* parameter to the constructor can be used to
  indicate that such values should be accepted:

  .. doctest::

     >>> import configparser

     >>> sample_config = """
     ... [mysqld]
     ...   user = mysql
     ...   pid-file = /var/run/mysqld/mysqld.pid
     ...   skip-external-locking
     ...   old_passwords = 1
     ...   skip-bdb
     ...   # we don't need ACID today
     ...   skip-innodb
     ... """
     >>> config = configparser.ConfigParser(allow_no_value=True)
     >>> config.read_string(sample_config)

     >>> # Settings with values are treated as before:
     >>> config["mysqld"]["user"]
     'mysql'

     >>> # Settings without values provide None:
     >>> config["mysqld"]["skip-bdb"]

     >>> # Settings which aren't specified still raise an error:
     >>> config["mysqld"]["does-not-exist"]
     Traceback (most recent call last):
       ...
     KeyError: 'does-not-exist'

* *delimiters*, default value: ``('=', ':')``

  Delimiters are substrings that delimit keys from values within a section. The
  first occurence of a delimiting substring on a line is considered a delimiter.
  This means values (but not keys) can contain the delimiters.

  See also the *space_around_delimiters* argument to
  :meth:`ConfigParser.write`.

* *comment_prefixes*, default value: ``('#', ';')``

* *inline_comment_prefixes*, default value: ``None``

  Comment prefixes are strings that indicate the start of a valid comment within
  a config file. *comment_prefixes* are used only on otherwise empty lines
  (optionally indented) whereas *inline_comment_prefixes* can be used after
  every valid value (e.g.  section names, options and empty lines as well). By
  default inline comments are disabled and ``'#'`` and ``';'`` are used as
  prefixes for whole line comments.

  .. versionchanged:: 3.2
     In previous versions of :mod:`configparser` behaviour matched
     ``comment_prefixes=('#',';')`` and ``inline_comment_prefixes=(';',)``.

  Please note that config parsers don't support escaping of comment prefixes so
  using *inline_comment_prefixes* may prevent users from specifying option
  values with characters used as comment prefixes. When in doubt, avoid setting
  *inline_comment_prefixes*. In any circumstances, the only way of storing
  comment prefix characters at the beginning of a line in multiline values is to
  interpolate the prefix, for example::

    >>> from configparser import ConfigParser, ExtendedInterpolation
    >>> parser = ConfigParser(interpolation=ExtendedInterpolation())
    >>> # the default BasicInterpolation could be used as well
    >>> parser.read_string("""
    ... [DEFAULT]
    ... hash = #
    ...
    ... [hashes]
    ... shebang =
    ...   ${hash}!/usr/bin/env python
    ...   ${hash} -*- coding: utf-8 -*-
    ...
    ... extensions =
    ...   enabled_extension
    ...   another_extension
    ...   #disabled_by_comment
    ...   yet_another_extension
    ...
    ... interpolation not necessary = if # is not at line start
    ... even in multiline values = line #1
    ...   line #2
    ...   line #3
    ... """)
    >>> print(parser['hashes']['shebang'])

    #!/usr/bin/env python
    # -*- coding: utf-8 -*-
    >>> print(parser['hashes']['extensions'])

    enabled_extension
    another_extension
    yet_another_extension
    >>> print(parser['hashes']['interpolation not necessary'])
    if # is not at line start
    >>> print(parser['hashes']['even in multiline values'])
    line #1
    line #2
    line #3

* *strict*, default value: ``True``

  When set to ``True``, the parser will not allow for any section or option
  duplicates while reading from a single source (using :meth:`read_file`,
  :meth:`read_string` or :meth:`read_dict`). It is recommended to use strict
  parsers in new applications.

  .. versionchanged:: 3.2
     In previous versions of :mod:`configparser` behaviour matched
     ``strict=False``.

* *empty_lines_in_values*, default value: ``True``

  In config parsers, values can span multiple lines as long as they are
  indented more than the key that holds them.  By default parsers also let
  empty lines to be parts of values.  At the same time, keys can be arbitrarily
  indented themselves to improve readability.  In consequence, when
  configuration files get big and complex, it is easy for the user to lose
  track of the file structure.  Take for instance:

  .. code-block:: ini

     [Section]
     key = multiline
       value with a gotcha

      this = is still a part of the multiline value of 'key'

  This can be especially problematic for the user to see if she's using a
  proportional font to edit the file.  That is why when your application does
  not need values with empty lines, you should consider disallowing them.  This
  will make empty lines split keys every time.  In the example above, it would
  produce two keys, ``key`` and ``this``.

* *default_section*, default value: ``configparser.DEFAULTSECT`` (that is:
  ``"DEFAULT"``)

  The convention of allowing a special section of default values for other
  sections or interpolation purposes is a powerful concept of this library,
  letting users create complex declarative configurations. This section is
  normally called ``"DEFAULT"`` but this can be customized to point to any
  other valid section name. Some typical values include: ``"general"`` or
  ``"common"``. The name provided is used for recognizing default sections when
  reading from any source and is used when writing configuration back to
  a file. Its current value can be retrieved using the
  ``parser_instance.default_section`` attribute and may be modified at runtime
  (i.e. to convert files from one format to another).

* *interpolation*, default value: ``configparser.BasicInterpolation``

  Interpolation behaviour may be customized by providing a custom handler
  through the *interpolation* argument. ``None`` can be used to turn off
  interpolation completely, ``ExtendedInterpolation()`` provides a more
  advanced variant inspired by ``zc.buildout``. More on the subject in the
  `dedicated documentation section <#interpolation-of-values>`_.
  :class:`RawConfigParser` has a default value of ``None``.


More advanced customization may be achieved by overriding default values of
these parser attributes.  The defaults are defined on the classes, so they
may be overriden by subclasses or by attribute assignment.

.. attribute:: BOOLEAN_STATES

  By default when using :meth:`getboolean`, config parsers consider the
  following values ``True``: ``'1'``, ``'yes'``, ``'true'``, ``'on'`` and the
  following values ``False``: ``'0'``, ``'no'``, ``'false'``, ``'off'``.  You
  can override this by specifying a custom dictionary of strings and their
  Boolean outcomes. For example:

  .. doctest::

     >>> custom = configparser.ConfigParser()
     >>> custom['section1'] = {'funky': 'nope'}
     >>> custom['section1'].getboolean('funky')
     Traceback (most recent call last):
     ...
     ValueError: Not a boolean: nope
     >>> custom.BOOLEAN_STATES = {'sure': True, 'nope': False}
     >>> custom['section1'].getboolean('funky')
     False

  Other typical Boolean pairs include ``accept``/``reject`` or
  ``enabled``/``disabled``.

.. method:: optionxform(option)

  This method transforms option names on every read, get, or set
  operation.  The default converts the name to lowercase.  This also
  means that when a configuration file gets written, all keys will be
  lowercase.  Override this method if that's unsuitable.
  For example:

  .. doctest::

     >>> config = """
     ... [Section1]
     ... Key = Value
     ...
     ... [Section2]
     ... AnotherKey = Value
     ... """
     >>> typical = configparser.ConfigParser()
     >>> typical.read_string(config)
     >>> list(typical['Section1'].keys())
     ['key']
     >>> list(typical['Section2'].keys())
     ['anotherkey']
     >>> custom = configparser.RawConfigParser()
     >>> custom.optionxform = lambda option: option
     >>> custom.read_string(config)
     >>> list(custom['Section1'].keys())
     ['Key']
     >>> list(custom['Section2'].keys())
     ['AnotherKey']

.. attribute:: SECTCRE

  A compiled regular expression used to parse section headers. The default
  matches ``[section]`` to the name ``"section"``. Whitespace is considered part
  of the section name, thus ``[  larch  ]`` will be read as a section of name
  ``"  larch  "``. Override this attribute if that's unsuitable.  For example:

  .. doctest::

     >>> config = """
     ... [Section 1]
     ... option = value
     ...
     ... [  Section 2  ]
     ... another = val
     ... """
     >>> typical = ConfigParser()
     >>> typical.read_string(config)
     >>> typical.sections()
     ['Section 1', '  Section 2  ']
     >>> custom = ConfigParser()
     >>> custom.SECTCRE = re.compile(r"\[ *(?P<header>[^]]+?) *\]")
     >>> custom.read_string(config)
     >>> custom.sections()
     ['Section 1', 'Section 2']

  .. note::

     While ConfigParser objects also use an ``OPTCRE`` attribute for recognizing
     option lines, it's not recommended to override it because that would
     interfere with constructor options *allow_no_value* and *delimiters*.


Legacy API Examples
-------------------

Mainly because of backwards compatibility concerns, :mod:`configparser`
provides also a legacy API with explicit ``get``/``set`` methods.  While there
are valid use cases for the methods outlined below, mapping protocol access is
preferred for new projects.  The legacy API is at times more advanced,
low-level and downright counterintuitive.

An example of writing to a configuration file::

   import configparser

   config = configparser.RawConfigParser()

   # Please note that using RawConfigParser's set functions, you can assign
   # non-string values to keys internally, but will receive an error when
   # attempting to write to a file or when you get it in non-raw mode. Setting
   # values using the mapping protocol or ConfigParser's set() does not allow
   # such assignments to take place.
   config.add_section('Section1')
   config.set('Section1', 'int', '15')
   config.set('Section1', 'bool', 'true')
   config.set('Section1', 'float', '3.1415')
   config.set('Section1', 'baz', 'fun')
   config.set('Section1', 'bar', 'Python')
   config.set('Section1', 'foo', '%(bar)s is %(baz)s!')

   # Writing our configuration file to 'example.cfg'
   with open('example.cfg', 'w') as configfile:
       config.write(configfile)

An example of reading the configuration file again::

   import configparser

   config = configparser.RawConfigParser()
   config.read('example.cfg')

   # getfloat() raises an exception if the value is not a float
   # getint() and getboolean() also do this for their respective types
   float = config.getfloat('Section1', 'float')
   int = config.getint('Section1', 'int')
   print(float + int)

   # Notice that the next output does not interpolate '%(bar)s' or '%(baz)s'.
   # This is because we are using a RawConfigParser().
   if config.getboolean('Section1', 'bool'):
       print(config.get('Section1', 'foo'))

To get interpolation, use :class:`ConfigParser`::

   import configparser

   cfg = configparser.ConfigParser()
   cfg.read('example.cfg')

   # Set the optional *raw* argument of get() to True if you wish to disable
   # interpolation in a single get operation.
   print(cfg.get('Section1', 'foo', raw=False)) # -> "Python is fun!"
   print(cfg.get('Section1', 'foo', raw=True))  # -> "%(bar)s is %(baz)s!"

   # The optional *vars* argument is a dict with members that will take
   # precedence in interpolation.
   print(cfg.get('Section1', 'foo', vars={'bar': 'Documentation',
                                             'baz': 'evil'}))

   # The optional *fallback* argument can be used to provide a fallback value
   print(cfg.get('Section1', 'foo'))
         # -> "Python is fun!"

   print(cfg.get('Section1', 'foo', fallback='Monty is not.'))
         # -> "Python is fun!"

   print(cfg.get('Section1', 'monster', fallback='No such things as monsters.'))
         # -> "No such things as monsters."

   # A bare print(cfg.get('Section1', 'monster')) would raise NoOptionError
   # but we can also use:

   print(cfg.get('Section1', 'monster', fallback=None))
         # -> None

Default values are available in both types of ConfigParsers.  They are used in
interpolation if an option used is not defined elsewhere. ::

   import configparser

   # New instance with 'bar' and 'baz' defaulting to 'Life' and 'hard' each
   config = configparser.ConfigParser({'bar': 'Life', 'baz': 'hard'})
   config.read('example.cfg')

   print(config.get('Section1', 'foo')) # -> "Python is fun!"
   config.remove_option('Section1', 'bar')
   config.remove_option('Section1', 'baz')
   print(config.get('Section1', 'foo')) # -> "Life is hard!"


.. _configparser-objects:

ConfigParser Objects
--------------------

.. class:: ConfigParser(defaults=None, dict_type=collections.OrderedDict, allow_no_value=False, delimiters=('=', ':'), comment_prefixes=('#', ';'), inline_comment_prefixes=None, strict=True, empty_lines_in_values=True, default_section=configparser.DEFAULTSECT, interpolation=BasicInterpolation())

   The main configuration parser.  When *defaults* is given, it is initialized
   into the dictionary of intrinsic defaults.  When *dict_type* is given, it
   will be used to create the dictionary objects for the list of sections, for
   the options within a section, and for the default values.

   When *delimiters* is given, it is used as the set of substrings that
   divide keys from values.  When *comment_prefixes* is given, it will be used
   as the set of substrings that prefix comments in otherwise empty lines.
   Comments can be indented. When *inline_comment_prefixes* is given, it will be
   used as the set of substrings that prefix comments in non-empty lines.

   When *strict* is ``True`` (the default), the parser won't allow for
   any section or option duplicates while reading from a single source (file,
   string or dictionary), raising :exc:`DuplicateSectionError` or
   :exc:`DuplicateOptionError`.  When *empty_lines_in_values* is ``False``
   (default: ``True``), each empty line marks the end of an option.  Otherwise,
   internal empty lines of a multiline option are kept as part of the value.
   When *allow_no_value* is ``True`` (default: ``False``), options without
   values are accepted; the value held for these is ``None`` and they are
   serialized without the trailing delimiter.

   When *default_section* is given, it specifies the name for the special
   section holding default values for other sections and interpolation purposes
   (normally named ``"DEFAULT"``). This value can be retrieved and changed on
   runtime using the ``default_section`` instance attribute.

   Interpolation behaviour may be customized by providing a custom handler
   through the *interpolation* argument. ``None`` can be used to turn off
   interpolation completely, ``ExtendedInterpolation()`` provides a more
   advanced variant inspired by ``zc.buildout``. More on the subject in the
   `dedicated documentation section <#interpolation-of-values>`_.

   All option names used in interpolation will be passed through the
   :meth:`optionxform` method just like any other option name reference.  For
   example, using the default implementation of :meth:`optionxform` (which
   converts option names to lower case), the values ``foo %(bar)s`` and ``foo
   %(BAR)s`` are equivalent.

   .. versionchanged:: 3.1
      The default *dict_type* is :class:`collections.OrderedDict`.

   .. versionchanged:: 3.2
      *allow_no_value*, *delimiters*, *comment_prefixes*, *strict*,
      *empty_lines_in_values*, *default_section* and *interpolation* were
      added.


   .. method:: defaults()

      Return a dictionary containing the instance-wide defaults.


   .. method:: sections()

      Return a list of the sections available; the *default section* is not
      included in the list.


   .. method:: add_section(section)

      Add a section named *section* to the instance.  If a section by the given
      name already exists, :exc:`DuplicateSectionError` is raised.  If the
      *default section* name is passed, :exc:`ValueError` is raised.  The name
      of the section must be a string; if not, :exc:`TypeError` is raised.

      .. versionchanged:: 3.2
         Non-string section names raise :exc:`TypeError`.


   .. method:: has_section(section)

      Indicates whether the named *section* is present in the configuration.
      The *default section* is not acknowledged.


   .. method:: options(section)

      Return a list of options available in the specified *section*.


   .. method:: has_option(section, option)

      If the given *section* exists, and contains the given *option*, return
      :const:`True`; otherwise return :const:`False`. If the specified
      *section* is :const:`None` or an empty string, DEFAULT is assumed.


   .. method:: read(filenames, encoding=None)

      Attempt to read and parse a list of filenames, returning a list of
      filenames which were successfully parsed.  If *filenames* is a string, it
      is treated as a single filename.  If a file named in *filenames* cannot
      be opened, that file will be ignored.  This is designed so that you can
      specify a list of potential configuration file locations (for example,
      the current directory, the user's home directory, and some system-wide
      directory), and all existing configuration files in the list will be
      read.  If none of the named files exist, the :class:`ConfigParser`
      instance will contain an empty dataset.  An application which requires
      initial values to be loaded from a file should load the required file or
      files using :meth:`read_file` before calling :meth:`read` for any
      optional files::

         import configparser, os

         config = configparser.ConfigParser()
         config.read_file(open('defaults.cfg'))
         config.read(['site.cfg', os.path.expanduser('~/.myapp.cfg')],
                     encoding='cp1250')

      .. versionadded:: 3.2
         The *encoding* parameter.  Previously, all files were read using the
         default encoding for :func:`open`.


   .. method:: read_file(f, source=None)

      Read and parse configuration data from *f* which must be an iterable
      yielding Unicode strings (for example files opened in text mode).

      Optional argument *source* specifies the name of the file being read.  If
      not given and *f* has a :attr:`name` attribute, that is used for
      *source*; the default is ``'<???>'``.

      .. versionadded:: 3.2
         Replaces :meth:`readfp`.

   .. method:: read_string(string, source='<string>')

      Parse configuration data from a string.

      Optional argument *source* specifies a context-specific name of the
      string passed.  If not given, ``'<string>'`` is used.  This should
      commonly be a filesystem path or a URL.

      .. versionadded:: 3.2


   .. method:: read_dict(dictionary, source='<dict>')

      Load configuration from any object that provides a dict-like ``items()``
      method.  Keys are section names, values are dictionaries with keys and
      values that should be present in the section.  If the used dictionary
      type preserves order, sections and their keys will be added in order.
      Values are automatically converted to strings.

      Optional argument *source* specifies a context-specific name of the
      dictionary passed.  If not given, ``<dict>`` is used.

      This method can be used to copy state between parsers.

      .. versionadded:: 3.2


   .. method:: get(section, option, *, raw=False, vars=None[, fallback])

      Get an *option* value for the named *section*.  If *vars* is provided, it
      must be a dictionary.  The *option* is looked up in *vars* (if provided),
      *section*, and in *DEFAULTSECT* in that order.  If the key is not found
      and *fallback* is provided, it is used as a fallback value.  ``None`` can
      be provided as a *fallback* value.

      All the ``'%'`` interpolations are expanded in the return values, unless
      the *raw* argument is true.  Values for interpolation keys are looked up
      in the same manner as the option.

      .. versionchanged:: 3.2
         Arguments *raw*, *vars* and *fallback* are keyword only to protect
         users from trying to use the third argument as the *fallback* fallback
         (especially when using the mapping protocol).


   .. method:: getint(section, option, *, raw=False, vars=None[, fallback])

      A convenience method which coerces the *option* in the specified *section*
      to an integer.  See :meth:`get` for explanation of *raw*, *vars* and
      *fallback*.


   .. method:: getfloat(section, option, *, raw=False, vars=None[, fallback])

      A convenience method which coerces the *option* in the specified *section*
      to a floating point number.  See :meth:`get` for explanation of *raw*,
      *vars* and *fallback*.


   .. method:: getboolean(section, option, *, raw=False, vars=None[, fallback])

      A convenience method which coerces the *option* in the specified *section*
      to a Boolean value.  Note that the accepted values for the option are
      ``'1'``, ``'yes'``, ``'true'``, and ``'on'``, which cause this method to
      return ``True``, and ``'0'``, ``'no'``, ``'false'``, and ``'off'``, which
      cause it to return ``False``.  These string values are checked in a
      case-insensitive manner.  Any other value will cause it to raise
      :exc:`ValueError`.  See :meth:`get` for explanation of *raw*, *vars* and
      *fallback*.


   .. method:: items([section], raw=False, vars=None)

      When *section* is not given, return a list of *section_name*,
      *section_proxy* pairs, including DEFAULTSECT.

      Otherwise, return a list of *name*, *value* pairs for the options in the
      given *section*.  Optional arguments have the same meaning as for the
      :meth:`get` method.

      .. versionchanged:: 3.2
         Items present in *vars* no longer appear in the result. The previous
         behaviour mixed actual parser options with variables provided for
         interpolation.

   .. method:: set(section, option, value)

      If the given section exists, set the given option to the specified value;
      otherwise raise :exc:`NoSectionError`.  *option* and *value* must be
      strings; if not, :exc:`TypeError` is raised.


   .. method:: write(fileobject, space_around_delimiters=True)

      Write a representation of the configuration to the specified :term:`file
      object`, which must be opened in text mode (accepting strings).  This
      representation can be parsed by a future :meth:`read` call.  If
      *space_around_delimiters* is true, delimiters between
      keys and values are surrounded by spaces.


   .. method:: remove_option(section, option)

      Remove the specified *option* from the specified *section*.  If the
      section does not exist, raise :exc:`NoSectionError`.  If the option
      existed to be removed, return :const:`True`; otherwise return
      :const:`False`.


   .. method:: remove_section(section)

      Remove the specified *section* from the configuration.  If the section in
      fact existed, return ``True``.  Otherwise return ``False``.


   .. method:: optionxform(option)

      Transforms the option name *option* as found in an input file or as passed
      in by client code to the form that should be used in the internal
      structures.  The default implementation returns a lower-case version of
      *option*; subclasses may override this or client code can set an attribute
      of this name on instances to affect this behavior.

      You don't need to subclass the parser to use this method, you can also
      set it on an instance, to a function that takes a string argument and
      returns a string.  Setting it to ``str``, for example, would make option
      names case sensitive::

         cfgparser = ConfigParser()
         cfgparser.optionxform = str

      Note that when reading configuration files, whitespace around the option
      names is stripped before :meth:`optionxform` is called.


   .. method:: readfp(fp, filename=None)

      .. deprecated:: 3.2
         Use :meth:`read_file` instead.

      .. versionchanged:: 3.2
         :meth:`readfp` now iterates on *f* instead of calling ``f.readline()``.

      For existing code calling :meth:`readfp` with arguments which don't
      support iteration, the following generator may be used as a wrapper
      around the file-like object::

         def readline_generator(f):
             line = f.readline()
             while line:
                 yield line
                 line = f.readline()

      Instead of ``parser.readfp(f)`` use
      ``parser.read_file(readline_generator(f))``.


.. data:: MAX_INTERPOLATION_DEPTH

   The maximum depth for recursive interpolation for :meth:`get` when the *raw*
   parameter is false.  This is relevant only when the default *interpolation*
   is used.


.. _rawconfigparser-objects:

RawConfigParser Objects
-----------------------

.. class:: RawConfigParser(defaults=None, dict_type=collections.OrderedDict, \
                           allow_no_value=False, *, delimiters=('=', ':'), \
                           comment_prefixes=('#', ';'), \
                           inline_comment_prefixes=None, strict=True, \
                           empty_lines_in_values=True, \
                           default_section=configparser.DEFAULTSECT[, \
                           interpolation])

   Legacy variant of the :class:`ConfigParser` with interpolation disabled
   by default and unsafe ``add_section`` and ``set`` methods.

   .. note::
      Consider using :class:`ConfigParser` instead which checks types of
      the values to be stored internally. If you don't want interpolation, you
      can use ``ConfigParser(interpolation=None)``.


   .. method:: add_section(section)

      Add a section named *section* to the instance.  If a section by the given
      name already exists, :exc:`DuplicateSectionError` is raised.  If the
      *default section* name is passed, :exc:`ValueError` is raised.

      Type of *section* is not checked which lets users create non-string named
      sections. This behaviour is unsupported and may cause internal errors.


   .. method:: set(section, option, value)

      If the given section exists, set the given option to the specified value;
      otherwise raise :exc:`NoSectionError`.  While it is possible to use
      :class:`RawConfigParser` (or :class:`ConfigParser` with *raw* parameters
      set to true) for *internal* storage of non-string values, full
      functionality (including interpolation and output to files) can only be
      achieved using string values.

      This method lets users assign non-string values to keys internally.  This
      behaviour is unsupported and will cause errors when attempting to write
      to a file or get it in non-raw mode.  **Use the mapping protocol API**
      which does not allow such assignments to take place.


Exceptions
----------

.. exception:: Error

   Base class for all other :mod:`configparser` exceptions.


.. exception:: NoSectionError

   Exception raised when a specified section is not found.


.. exception:: DuplicateSectionError

   Exception raised if :meth:`add_section` is called with the name of a section
   that is already present or in strict parsers when a section if found more
   than once in a single input file, string or dictionary.

   .. versionadded:: 3.2
      Optional ``source`` and ``lineno`` attributes and arguments to
      :meth:`__init__` were added.


.. exception:: DuplicateOptionError

   Exception raised by strict parsers if a single option appears twice during
   reading from a single file, string or dictionary. This catches misspellings
   and case sensitivity-related errors, e.g. a dictionary may have two keys
   representing the same case-insensitive configuration key.


.. exception:: NoOptionError

   Exception raised when a specified option is not found in the specified
   section.


.. exception:: InterpolationError

   Base class for exceptions raised when problems occur performing string
   interpolation.


.. exception:: InterpolationDepthError

   Exception raised when string interpolation cannot be completed because the
   number of iterations exceeds :const:`MAX_INTERPOLATION_DEPTH`.  Subclass of
   :exc:`InterpolationError`.


.. exception:: InterpolationMissingOptionError

   Exception raised when an option referenced from a value does not exist.
   Subclass of :exc:`InterpolationError`.


.. exception:: InterpolationSyntaxError

   Exception raised when the source text into which substitutions are made does
   not conform to the required syntax.  Subclass of :exc:`InterpolationError`.


.. exception:: MissingSectionHeaderError

   Exception raised when attempting to parse a file which has no section
   headers.


.. exception:: ParsingError

   Exception raised when errors occur attempting to parse a file.

   .. versionchanged:: 3.2
      The ``filename`` attribute and :meth:`__init__` argument were renamed to
      ``source`` for consistency.


.. rubric:: Footnotes

.. [1] Config parsers allow for heavy customization.  If you are interested in
       changing the behaviour outlined by the footnote reference, consult the
       `Customizing Parser Behaviour`_ section.