Pythonic command line arguments parser, that will make you smile

docopt creates beautiful command-line interfaces

Video introduction to docopt: PyCon UK 2012: Create beautiful
command-line interfaces with Python

New in version 0.6.1:

  • Fix issue #85
    which caused improper handling of [options] shortcut
    if it was present several times.

New in version 0.6.0:

  • New argument options_first, disallows interspersing options
    and arguments. If you supply options_first=True to
    docopt, it will interpret all arguments as positional
    arguments after first positional argument.

  • If option with argument could be repeated, its default value
    will be interpreted as space-separated list. E.g. with
    [default: ./here ./there] will be interpreted as
    ['./here', './there'].

Breaking changes:

  • Meaning of [options] shortcut slightly changed. Previously
    it meant "any known option". Now it means "any option not in
    . This avoids the situation when an option is
    allowed to be repeated unintentionally.

  • argv is None by default, not sys.argv[1:].
    This allows docopt to always use the latest sys.argv,
    not sys.argv during import time.

Isn't it awesome how optparse and argparse generate help
messages based on your code?!

Hell no! You know what's awesome? It's when the option parser is
generated based on the beautiful help message that you write yourself!
This way you don't need to write this stupid repeatable parser-code,
and instead can write only the help message--the way you want it.

docopt helps you create most beautiful command-line interfaces

"""Naval Fate.

Usage: ship new <name>... ship <name> move <x> <y> [--speed=<kn>] ship shoot <x> <y> mine (set|remove) <x> <y> [--moored | --drifting] (-h | --help) --version

-h --help Show this screen.
--version Show version.
--speed=<kn> Speed in knots [default: 10].
--moored Moored (anchored) mine.
--drifting Drifting mine.

from docopt import docopt

if name == 'main':
arguments = docopt(doc, version='Naval Fate 2.0')

Beat that! The option parser is generated based on the docstring above
that is passed to docopt function. docopt parses the usage
pattern ("Usage: ...") and option descriptions (lines starting
with dash "-") and ensures that the program invocation matches the
usage pattern; it parses options, arguments and commands based on
that. The basic idea is that a good help message has all necessary
information in it to make a parser

Also, PEP 257 recommends
putting help message in the module docstrings.


Use pip or easy_install:

pip install docopt==0.6.2

Alternatively, you can just drop file into your
project--it is self-contained.

docopt is tested with Python 2.6, 2.7, 3.3, 3.4, 3.5 and PyPy.


You can run unit tests using the command:

python test


from docopt import docopt

docopt(doc, argv=None, help=True, version=None, options_first=False)

docopt takes 1 required and 4 optional arguments:

  • doc could be a module docstring (doc) or some other
    string that contains a help message that will be parsed to
    create the option parser. The simple rules of how to write such a
    help message are given in next sections. Here is a quick example of
    such a string:

"""Usage: [-hso FILE] [--quiet | --verbose] [INPUT ...]

-h --help show this
-s --sorted sorted output
-o FILE specify output file [default: ./test.txt]
--quiet print less text
--verbose print more text


  • argv is an optional argument vector; by default docopt uses
    the argument vector passed to your program (sys.argv[1:]).
    Alternatively you can supply a list of strings like ['--verbose',
    '-o', 'hai.txt']

  • help, by default True, specifies whether the parser should
    automatically print the help message (supplied as doc) and
    terminate, in case -h or --help option is encountered
    (options should exist in usage pattern, more on that below). If you
    want to handle -h or --help options manually (as other
    options), set help=False.

  • version, by default None, is an optional argument that
    specifies the version of your program. If supplied, then, (assuming
    --version option is mentioned in usage pattern) when parser
    encounters the --version option, it will print the supplied
    version and terminate. version could be any printable object,
    but most likely a string, e.g. "2.1.0rc1".

    Note, when docopt is set to automatically handle -h,
    --help and --version options, you still need to mention
    them in usage pattern for this to work. Also, for your users to
    know about them.

  • options_first, by default False. If set to True will
    disallow mixing options and positional argument. I.e. after first
    positional argument, all arguments will be interpreted as positional
    even if the look like options. This can be used for strict
    compatibility with POSIX, or if you want to dispatch your arguments
    to other programs.

The return value is a simple dictionary with options, arguments
and commands as keys, spelled exactly like in your help message. Long
versions of options are given priority. For example, if you invoke the
top example as: ship Guardian move 100 150 --speed=15

the return dictionary will be:

{'--drifting': False,    'mine': False,
'--help': False, 'move': True,
'--moored': False, 'new': False,
'--speed': '15', 'remove': False,
'--version': False, 'set': False,
'<name>': ['Guardian'], 'ship': True,
'<x>': '100', 'shoot': False,
'<y>': '150'}

Help message format

Help message consists of 2 parts:

  • Usage pattern, e.g.:

    Usage: [-hso FILE] [--quiet | --verbose] [INPUT ...]

  • Option descriptions, e.g.:

    -h --help    show this
    -s --sorted sorted output
    -o FILE specify output file [default: ./test.txt]
    --quiet print less text
    --verbose print more text

Their format is described below; other text is ignored.

Usage pattern format

Usage pattern is a substring of doc that starts with
usage: (case insensitive) and ends with a visibly empty line.
Minimum example:



The first word after usage: is interpreted as your program's name.
You can specify your program's name several times to signify several
exclusive patterns:



Each pattern can consist of the following elements:

  • <arguments>, ARGUMENTS. Arguments are specified as either
    upper-case words, e.g. CONTENT-PATH or words
    surrounded by angular brackets: <content-path>.

  • --options. Options are words started with dash (-), e.g.
    --output, -o. You can "stack" several of one-letter
    options, e.g. -oiv which will be the same as -o -i -v. The
    options can have arguments, e.g. --input=FILE or -i FILE or
    even -iFILE. However it is important that you specify option
    descriptions if you want your option to have an argument, a default
    value, or specify synonymous short/long versions of the option (see
    next section on option descriptions).

  • commands are words that do not follow the described above
    conventions of --options or <arguments> or ARGUMENTS,
    plus two special commands: dash "-" and double dash "--"
    (see below).

Use the following constructs to specify patterns:

  • [ ] (brackets) optional elements. e.g.:
    [-hvqo FILE]

  • ( ) (parens) required elements. All elements that are not
    put in [ ] are also required, e.g.:
    --path=<path> <file>...
    is the same as
    (--path=<path> <file>...)
    . (Note, "required options" might be not
    a good idea for your users).

  • | (pipe) mutually exclusive elements. Group them using (
    if one of the mutually exclusive elements is required: (--clockwise | --counter-clockwise) TIME. Group
    them using [ ] if none of the mutually-exclusive elements are
    required: [--left | --right].

  • ... (ellipsis) one or more elements. To specify that
    arbitrary number of repeating elements could be accepted, use
    ellipsis (...), e.g. FILE ... means one or
    more FILE-s are accepted. If you want to accept zero or more
    elements, use brackets, e.g.: [FILE ...]. Ellipsis
    works as a unary operator on the expression to the left.

  • [options] (case sensitive) shortcut for any options. You can
    use it if you want to specify that the usage pattern could be
    provided with any options defined below in the option-descriptions
    and do not want to enumerate them all in usage-pattern.

  • "[--]". Double dash "--" is used by convention to separate
    positional arguments that can be mistaken for options. In order to
    support this convention add "[--]" to your usage patterns.

  • "[-]". Single dash "-" is used by convention to signify that
    stdin is used instead of a file. To support this add "[-]"
    to your usage patterns. "-" acts as a normal command.

If your pattern allows to match argument-less option (a flag) several

Usage: [-v | -vv | -vvv]

then number of occurrences of the option will be counted. I.e.
args['-v'] will be 2 if program was invoked as my_program
. Same works for commands.

If your usage patterns allows to match same-named option with argument
or positional argument several times, the matched arguments will be
collected into a list:

Usage: <file> <file> --path=<path>...

I.e. invoked with file1 file2 --path=./here
the returned dict will contain args['<file>'] ==
['file1', 'file2']
and args['--path'] == ['./here', './there'].

Option descriptions format

Option descriptions consist of a list of options that you put
below your usage patterns.

It is necessary to list option descriptions in order to specify:

  • synonymous short and long options,

  • if an option has an argument,

  • if option's argument has a default value.

The rules are as follows:

  • Every line in doc that starts with - or -- (not counting
    spaces) is treated as an option description, e.g.:

    --verbose # GOOD
    -o FILE # GOOD
    Other: --bad # BAD, line does not start with dash "-"

  • To specify that option has an argument, put a word describing that
    argument after space (or equals "=" sign) as shown below. Follow
    either <angular-brackets> or UPPER-CASE convention for options'
    arguments. You can use comma if you want to separate options. In
    the example below, both lines are valid, however you are recommended
    to stick to a single style.:

    -o FILE --output=FILE       # without comma, with "=" sign
    -i <file>, --input <file> # with comma, without "=" sing

  • Use two spaces to separate options with their informal description:

    --verbose More text.   # BAD, will be treated as if verbose option had
    # an argument "More", so use 2 spaces instead
    -q Quit. # GOOD
    -o FILE Output file. # GOOD
    --stdout Use stdout. # GOOD, 2 spaces

  • If you want to set a default value for an option with an argument,
    put it into the option-description, in form [default:

    --coefficient=K  The K coefficient [default: 2.95]
    --output=FILE Output file [default: test.txt]
    --directory=DIR Some directory [default: ./]

  • If the option is not repeatable, the value inside [default: ...]
    will be interpreted as string. If it is repeatable, it will be
    splited into a list on whitespace:

    Usage: [--repeatable=<arg> --repeatable=<arg>]

    will be ['./here', './there']

    --repeatable=<arg> [default: ./here ./there]

    will be ['./here']

    --another-repeatable=<arg> [default: ./here]

    will be './here ./there', because it is not repeatable

    --not-repeatable=<arg> [default: ./here ./there]


We have an extensive list of examples which cover
every aspect of functionality of docopt. Try them out, read the
source if in doubt.

Subparsers, multi-level help and huge applications (like git)

If you want to split your usage-pattern into several, implement
multi-level help (with separate help-screen for each subcommand),
want to interface with existing scripts that don't use docopt, or
you're building the next "git", you will need the new options_first
parameter (described in API section above). To get you started quickly
we implemented a subset of git command-line interface as an example:

Data validation

docopt does one thing and does it well: it implements your
command-line interface. However it does not validate the input data.
On the other hand there are libraries like python schema which make validating data a
breeze. Take a look at
which uses schema to validate data and report an error to the

Using docopt with config-files

Often configuration files are used to provide default values which
could be overriden by command-line arguments. Since docopt
returns a simple dictionary it is very easy to integrate with
config-files written in JSON, YAML or INI formats. provides
and example of how to use docopt with JSON or INI config-file.


We would love to hear what you think about docopt on our issues

Make pull requests, report bugs, suggest ideas and discuss
docopt. You can also drop a line directly to

Porting docopt to other languages

We think docopt is so good, we want to share it beyond the Python
community! All official docopt ports to other languages can be found
under the docopt organization page
on GitHub.

If your favourite language isn't among then, you can always create a
port for it! You are encouraged to use the Python version as a
reference implementation. A Language-agnostic test suite is bundled
with Python implementation.

Porting discussion is on issues page.


docopt follows semantic versioning. The
first release with stable API will be 1.0.0 (soon). Until then, you
are encouraged to specify explicitly the version in your dependency
tools, e.g.:

pip install docopt==0.6.2

  • 0.6.2 Bugfix release.

  • 0.6.1 Bugfix release.

  • 0.6.0 options_first parameter.
    Breaking changes: Corrected [options] meaning.
    argv defaults to None.

  • 0.5.0 Repeated options/commands are counted or accumulated into a

  • 0.4.2 Bugfix release.

  • 0.4.0 Option descriptions become optional,
    support for "--" and "-" commands.

  • 0.3.0 Support for (sub)commands like git remote add.
    Introduce [options] shortcut for any options.
    Breaking changes: docopt returns dictionary.

  • 0.2.0 Usage pattern matching. Positional arguments parsing based on
    usage patterns.
    Breaking changes: docopt returns namespace (for arguments),
    not list. Usage pattern is formalized.

  • 0.1.0 Initial release. Options-parsing only (based on options