Doc/library/configparser.rst

: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 classes :class:`RawConfigParser` and
:class:`SafeConfigParser`.  They implement 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.


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.RawConfigParser()
   >>> 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.RawConfigParser()
   >>> 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, or may be entered on lines holding
values or section names.  In the latter case, they need to be preceded
by a whitespace character to be recognized as a comment.  For backwards
compatibility, by default only ``;`` starts an inline comment, while
``#`` does not [1]_.

On top of the core functionality, :class:`SafeConfigParser` supports
interpolation.  This means values can contain format strings which refer to
other values in the same section, or values in a special ``DEFAULT`` section
[1]_.  Additional defaults 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

   [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] ; after a useful line
   ; in an empty line
   after: a_value ; here's another comment
   inside: a         ;comment
           multiline ;comment
           value!    ;comment

      [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?

In the example above, :class:`SafeConfigParser` 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.

:class:`RawConfigParser` would simply return ``%(my_dir)s/Pictures`` as the
value of ``my_pictures`` and ``%(home_dir)s/lumberjack`` as the value of
``my_dir``.  Other features presented in the example are handled in the same
manner by both parsers.


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`` throws ``ValueError``.

* There are two parser-level methods in the legacy API that hide the dictionary
  interface and are incompatible:

  * ``parser.get(section, option, **kwargs)`` - the second argument is **not** a
    fallback value

  * ``parser.items(section)`` - this returns a list of *option*, *value* pairs
    for a specified ``section``

The mapping protocol is implemented on top of the existing legacy API so that
subclassing the original interface makes the mappings work as expected as well.
One difference is the explicit lack of support for the ``'__name__'`` special
key.  This is because the existing behavior of ``'__name__'`` is very
inconsistent and supporting it would only lead to problems.  Details `here
<http://mail.python.org/pipermail/python-dev/2010-July/102556.html>`_.


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 ``DEFAULTSECT``.  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.RawConfigParser()
     >>> 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.RawConfigParser()
     >>> 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
     ...   skip-innodb # we don't need ACID today
     ... """
     >>> config = configparser.RawConfigParser(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:`RawConfigParser.write`.

* *comment_prefixes*, default value: ``_COMPATIBLE`` (``'#'`` valid on empty
  lines, ``';'`` valid also on non-empty lines)

  Comment prefixes are strings that indicate the start of a valid comment
  within a config file.  The peculiar default value allows for comments starting
  with ``'#'`` or ``';'`` but only the latter can be used in a non-empty line.
  This is obviously dictated by backwards compatibiliy.  A more predictable
  approach would be to specify prefixes as ``('#', ';')`` which will allow for
  both prefixes to be used in non-empty lines.

  Please note that config parsers don't support escaping of comment prefixes so
  leaving characters out of *comment_prefixes* is a way of ensuring they can be
  used as parts of keys or values.

* *strict*, default value: ``False``

  If 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`).  The default is ``False`` only
  because of backwards compatibility reasons.  It is recommended to use strict
  parsers in new applications.

* *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``.


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.RawConfigParser()
     >>> 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.RawConfigParser()
     >>> 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']


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 and the raw mode of
   # ConfigParser's respective 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 SafeConfigParser'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:`SafeConfigParser` or, if
you absolutely have to, a :class:`ConfigParser`::

   import configparser

   cfg = configparser.SafeConfigParser()
   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 all three 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.SafeConfigParser({'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!"


.. _rawconfigparser-objects:

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

.. class:: RawConfigParser(defaults=None, dict_type=collections.OrderedDict, allow_no_value=False, delimiters=('=', ':'), comment_prefixes=_COMPATIBLE, strict=False, empty_lines_in_values=True)

   The basic 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 a line, both for the whole
   line and inline comments.  For backwards compatibility, the default value for
   *comment_prefixes* is a special value that indicates that ``;`` and ``#`` can
   start whole line comments while only ``;`` can start inline comments.

   When *strict* is ``True`` (default: ``False``), 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 presented for these is ``None``.

   This class does not support the magical interpolation behavior.

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

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


   .. method:: defaults()

      Return a dictionary containing the instance-wide defaults.


   .. method:: sections()

      Return a list of the sections available; ``DEFAULT`` 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 name
      ``DEFAULT`` (or any of it's case-insensitive variants) is passed,
      :exc:`ValueError` is raised.


   .. 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`.


   .. 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 the file or file-like object in
      *f* (only the :meth:`readline` method is used).  The file-like object
      must operate in text mode.  Specifically, it must return strings from
      :meth:`readline`.

      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 a dictionary.  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.

      .. versionadded:: 3.2

   .. method:: get(section, option, [vars, 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.

      .. versionchanged:: 3.2
         Arguments *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, [vars, fallback])

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


   .. method:: getfloat(section, option, [vars, fallback])

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


   .. method:: getboolean(section, option, [vars, 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 *vars* and
      *fallback*.


   .. method:: items(section)

      Return a list of *name*, *value* pairs for each option in the given
      *section*.


   .. 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.

      .. note::

         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.


   .. 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.


.. _configparser-objects:

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

.. warning::
   Whenever you can, consider using :class:`SafeConfigParser` which adds
   validation and escaping for the interpolation.

The :class:`ConfigParser` class extends some methods of the
:class:`RawConfigParser` interface, adding some optional arguments.

.. class:: ConfigParser(defaults=None, dict_type=collections.OrderedDict, allow_no_value=False, delimiters=('=', ':'), comment_prefixes=_COMPATIBLE, strict=False, empty_lines_in_values=True)

   Derived class of :class:`RawConfigParser` that implements the magical
   interpolation feature and adds optional arguments to the :meth:`get` and
   :meth:`items` methods.

   :class:`SafeConfigParser` is generally recommended over this class if you
   need interpolation.

   The values in *defaults* must be appropriate for the ``%()s`` string
   interpolation.  Note that ``'__name__'`` is an intrinsic default; its value
   is the section name, and will override any value provided in *defaults*.

   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* and *empty_lines_in_values* were added.


   .. method:: get(section, option, raw=False, [vars, 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, 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, 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, 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)

      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.


.. data:: MAX_INTERPOLATION_DEPTH

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


.. _safeconfigparser-objects:

SafeConfigParser Objects
------------------------

.. class:: SafeConfigParser(defaults=None, dict_type=collections.OrderedDict, allow_no_value=False, delimiters=('=', ':'), comment_prefixes=_COMPATIBLE, strict=False, empty_lines_in_values=True)

   Derived class of :class:`ConfigParser` that implements a variant of the
   magical interpolation feature.  This implementation is more predictable as
   it validates the interpolation syntax used within a configuration file.
   This class also enables escaping the interpolation character (a key can have
   ``%`` as part of the value by specifying ``%%`` in the file).

   Applications that don't require interpolation should use
   :class:`RawConfigParser`, otherwise :class:`SafeConfigParser` is the best
   option.

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

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


   The :class:`SafeConfigParser` class implements the same extended interface
   as :class:`ConfigParser`, with the following addition:

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

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


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.