`cmd2` is a tool for writing command-line interactive applications.  It is based on the Python Standard Library's `cmd` module, and can be used anyplace `cmd` is used simply by importing `cmd2` instead.

`cmd2` provides the following features, in addition to those already existing in `cmd`:

- Searchable command history
- Load commands from file, save to file, edit commands in file
- Multi-line commands
- Case-insensitive commands
- Special-character shortcut commands (beyond cmd's "@" and "!")
- Settable environment parameters
- Parsing commands with flags

Instructions for implementing each feature follow.

- Searchable command history

    All commands will automatically be tracked in the session's history, unless the command is listed in Cmd's excludeFromHistory attribute.  
    The history is accessed through the `history`, `list`, and `run` commands 
    (and their abbreviations: `hi`, `li`, `l`, `r`).
    If you wish to exclude some of your custom commands from the history, append their names
    to the list at Cmd.ExcludeFromHistory.

- Load commands from file, save to file, edit commands in file

    Type `help load`, `help save`, `help edit` for details.
  
- Multi-line commands

    Any command accepts multi-line input when its name is listed in `Cmd.multilineCommands`.
    The program will keep expecting input until a line ends with any of the characters 
    in `Cmd.terminators` .  The default terminators are `;` and `/n` (empty newline).
    
- Case-insensitive commands

    All commands are case-insensitive, unless `Cmd.caseInsensitive` is set to `False`.
  
- Special-character shortcut commands (beyond cmd's "@" and "!")

    To create a single-character shortcut for a command, update `Cmd.shortcuts`.
  
- Settable environment parameters

    To allow a user to change an environment parameter during program execution, 
    append the parameter's name to `Cmd.settable`.
    
- Parsing commands with flags

    To allow a command to parse flags:
  
    1. Create a flagset: `flags = flagReader.FlagSet([flagReader.Flag('option')])`
    2. Within the command's function, `(opts, arg) = flags.parse(arg)`
    3. `opts` is a dictionary whose keys are the flags given, and whose values
       are the arguments to those flags (if any).

- Catherine Devlin, catherinedevlin.blogspot.com

cmd2 can be installed with `easy_install cmd2`

Cheese Shop page: http://pypi.python.org/pypi/cmd2/0.1

Example cmd2 application (cmd2_example.py) ::

    from cmd2 import Cmd, flagReader
    
    class CmdLineApp(Cmd):
        multilineCommands = ['orate']
        Cmd.shortcuts.update({'&': 'speak'})
        maxrepeats = 3
        Cmd.settable.append('maxrepeats')
        speakflags = flagReader.FlagSet([flagReader.Flag('piglatin'),
                                         flagReader.Flag('shout'),
                                         flagReader.Flag('repeat', nargs=1)
                                         ])                
        def do_speak(self, arg):
            """Repeats what you tell me to.
            
            args: --piglatin, -p: translate to Pig Latin
                  --shout, -s: emulate internet newbie
                  --repeat (nTimes), -r: be redundant"""
            (options, arg) = self.speakflags.parse(arg)
            
            if options.has_key('piglatin'):
                arg = '%s%say' % (arg[1:], arg[0])
            if options.has_key('shout'):
                arg = arg.upper()            
            repetitions = options.get('repeat')
            repetitions = int(repetitions[0]) if repetitions else 1
            for i in range(min(repetitions, self.maxrepeats)):
                self.stdout.write(arg)
                self.stdout.write('\n')
                # self.stdout.write is better than "print", because Cmd can be 
                # initialized with a non-standard output destination
        do_say = do_speak     # now "say" is a synonym for "speak"
        do_orate = do_speak   # another synonym, but this one takes multi-line input
            
    app = CmdLineApp()
    app.cmdloop()    

Sample session using the above code ::

    c:\cmd2>python cmd2_example.py
    (Cmd) speak softly
    softly    
    (Cmd) speak --piglatin softly
    oftlysay
    (Cmd) speak -psr 2 softly
    OFTLYSAY
    OFTLYSAY
    (Cmd) speak --repeat 1000000 softly
    softly
    softly
    softly
    (Cmd) show maxrepeats
    maxrepeats: 3
    (Cmd) set maxrepeats 5
    maxrepeats - was: 3
    now: 5
    (Cmd) speak --repeat 1000000 softly
    softly
    softly
    softly
    softly
    softly
    (Cmd) orate blah blah
    > blah
    > and furthermore
    > blah
    >
    blah blah blah and furthermore blah
    (Cmd) &greetings
    greetings 
    (Cmd) history
    -------------------------[1]
    speak softly
    -------------------------[2]
    speak --piglatin softly
    -------------------------[3]
    speak -psr 2 softly
    -------------------------[4]
    speak --repeat 1000000 softly
    -------------------------[5]
    show maxrepeats
    -------------------------[6]
    set maxrepeats 5
    -------------------------[7]
    speak --repeat 1000000 softly
    -------------------------[8]
    orate blah blah
    blah
    and furthermore
    blah
    
    -------------------------[9]
    &greetings  
    (Cmd) run
    orate blah blah
    blah
    and furthermore
    blah
    
    blah blah blah and furthermore blah
    (Cmd) run 3
    speak -psr 2 softly
    OFTLYSAY
    OFTLYSAY
    (Cmd) history maxrepeats
    -------------------------[5]
    set maxrepeats
    -------------------------[6]
    set maxrepeats 5
    (Cmd)