Miscellaneous Features

Timer

Turn the timer setting on, and cmd2 will show the wall time it takes for each command to execute.

Exiting

Like many shell applications, cmd2 applications can be exited by pressing Ctrl-D on an empty line, or by executing the quit command.

select

Presents numbered options to user, as bash select.

app.select is called from within a method (not by the user directly; it is app.select, not app.do_select).

cmd2.Cmd.select

select(opts, prompt='Your choice? ')

Present a numbered menu to the user.

Modeled after the bash shell's SELECT. Returns the item chosen.

Argument opts can be:

| a single string -> will be split into one-word options | a list of strings -> will be offered as options | a list of tuples -> interpreted as (value, text), so that the return value can differ from the text advertised to the user

Source code in cmd2/cmd2.py

def select(self, opts: str | list[str] | list[tuple[Any, str | None]], prompt: str = 'Your choice? ') -> Any:
    """Present a numbered menu to the user.

    Modeled after the bash shell's SELECT.  Returns the item chosen.

    Argument ``opts`` can be:

      | a single string -> will be split into one-word options
      | a list of strings -> will be offered as options
      | a list of tuples -> interpreted as (value, text), so
                            that the return value can differ from
                            the text advertised to the user
    """
    local_opts: list[str] | list[tuple[Any, str | None]]
    if isinstance(opts, str):
        local_opts = cast(list[tuple[Any, str | None]], list(zip(opts.split(), opts.split(), strict=False)))
    else:
        local_opts = opts
    fulloptions: list[tuple[Any, str | None]] = []
    for opt in local_opts:
        if isinstance(opt, str):
            fulloptions.append((opt, opt))
        else:
            try:
                fulloptions.append((opt[0], opt[1]))
            except IndexError:
                fulloptions.append((opt[0], opt[0]))
    for idx, (_, text) in enumerate(fulloptions):
        self.poutput('  %2d. %s' % (idx + 1, text))  # noqa: UP031

    while True:
        try:
            response = self.read_input(prompt)
        except EOFError:
            response = ''
            self.poutput()
        except KeyboardInterrupt:
            self.poutput('^C')
            raise

        if not response:
            continue

        try:
            choice = int(response)
            if choice < 1:
                raise IndexError  # noqa: TRY301
            return fulloptions[choice - 1][0]
        except (ValueError, IndexError):
            self.poutput(f"'{response}' isn't a valid choice. Pick a number between 1 and {len(fulloptions)}:")

def do_eat(self, arg):
    sauce = self.select('sweet salty', 'Sauce? ')
    result = '{food} with {sauce} sauce, yum!'
    result = result.format(food=arg, sauce=sauce)
    self.stdout.write(result + '\n')

(Cmd) eat wheaties
    1. sweet
    2. salty
Sauce? 2
wheaties with salty sauce, yum!

Disabling Commands

cmd2 supports disabling commands during runtime. This is useful if certain commands should only be available when the application is in a specific state. When a command is disabled, it will not show up in the help menu or tab complete. If a user tries to run the command, a command-specific message supplied by the developer will be printed. The following functions support this feature.

• enable_command : Enable an individual command
• enable_category : Enable an entire category of commands
• disable_command : Disable an individual command and set the message that will print when this command is run or help is called on it while disabled
• disable_category : Disable an entire category of commands and set the message that will print when anything in this category is run or help is called on it while disabled

See the definitions of these functions for descriptions of their arguments.

See the do_enable_commands() and do_disable_commands() functions in the help_categories.py example for a demonstration.

Default to shell

Every cmd2 application can execute operating-system level (shell) commands with shell or a ! shortcut:

(Cmd) shell which python
/usr/bin/python
(Cmd) !which python
/usr/bin/python

However, if the parameter default_to_shell is True, then every thing entered which doesn't match another command will be attempted on the operating system. Only if that attempt fails (i.e., produces a nonzero return value) will the application's own default method be called.

(Cmd) which python
/usr/bin/python
(Cmd) my dog has fleas
sh: my: not found
*** Unknown syntax: my dog has fleas