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def complete(parser: ArgumentParser,
             shell: str = "bash",
             root_prefix: Opt[str] = None,
             preamble: Union[str, Dict] = "",
             choice_functions: Opt[Any] = None) -> str
  • shell: bash/zsh/tcsh
  • root_prefix: prefix for shell functions to avoid clashes (default: "_{parser.prog}")
  • preamble: mapping shell to text to prepend to generated script (e.g. {"bash": "_myprog_custom_function(){ echo hello }"})
  • choice_functions: deprecated

N.B. parser.add_argument().complete = ... can be used to define custom completions (e.g. filenames). See examples/


def add_argument_to(parser: ArgumentParser,
                    option_string: Union[str,
                                         List[str]] = "--print-completion",
                    help: str = "print shell completion script",
                    parent: Opt[ArgumentParser] = None,
                    preamble: Union[str, Dict] = "")
  • option_string: iff positional (no - prefix) then parser is assumed to actually be a subparser (subcommand mode)
  • parent: required in subcommand mode