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cmd2

Author: Catherine Devlin, http://catherinedevlin.blogspot.com

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
  • Redirection to file with >, >>; input from file with <
  • Bare '>', '>>' with no filename send output to paste buffer
  • Pipe output to shell commands with |
  • Simple transcript-based application testing

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 optparse options (flags)

    @options([make_option('-m', '--myoption', action="store_true", help="all about my option")])
    def do_myfunc(self, arg, opts):
        if opts.myoption:
            ...
    

    See Python standard library's optparse documentation: http://docs.python.org/lib/optparse-defining-options.html

cmd2 can be installed with easy_install cmd2

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

Example cmd2 application (example/example.py)

'''A sample application for cmd2.'''

from cmd2 import Cmd, make_option, options, Cmd2TestCase
import unittest, optparse, sys

class CmdLineApp(Cmd):
    multilineCommands = ['orate']
    Cmd.shortcuts.update({'&': 'speak'})
    maxrepeats = 3
    Cmd.settable.append('maxrepeats')

    @options([make_option('-p', '--piglatin', action="store_true", help="atinLay"),
              make_option('-s', '--shout', action="store_true", help="N00B EMULATION MODE"),
              make_option('-r', '--repeat', type="int", help="output [n] times")
             ])
    def do_speak(self, arg, opts=None):
        """Repeats what you tell me to."""
        arg = ''.join(arg)
        if opts.piglatin:
            arg = '%s%say' % (arg[1:], arg[0])
        if opts.shout:
            arg = arg.upper()
        repetitions = opts.repeat or 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

class TestMyAppCase(Cmd2TestCase):
    CmdApp = CmdLineApp
    transcriptFileName = 'exampleSession.txt'

parser = optparse.OptionParser()
parser.add_option('-t', '--test', dest='unittests', action='store_true', default=False, help='Run unit test suite')
(callopts, callargs) = parser.parse_args()
if callopts.unittests:
    sys.argv = [sys.argv[0]]  # the --test argument upsets unittest.main()
    unittest.main()
else:
    app = CmdLineApp()
    app.cmdloop()

The following is a sample session running example.py. Thanks to TestMyAppCase(Cmd2TestCase), it also serves as a test suite for example.py when saved as exampleSession.txt. Running python example.py -t will run all the commands in the transcript against example.py, verifying that the output produced matches the transcript.

example/exampleSession.txt:

(Cmd) help

Documented commands (type help <topic>):
========================================
_load  edit  history  li    load   pause  run   say  shell      show
ed     hi    l        list  orate  r      save  set  shortcuts  speak

Undocumented commands:
======================
EOF  cmdenvironment  eof  exit  help  q  quit

(Cmd) help say
Repeats what you tell me to.
Usage: speak [options] arg

Options:
  -h, --help            show this help message and exit
  -p, --piglatin        atinLay
  -s, --shout           N00B EMULATION MODE
  -r REPEAT, --repeat=REPEAT
                        output [n] times

(Cmd) say goodnight, Gracie
goodnight, Gracie
(Cmd) say -ps --repeat=5 goodnight, Gracie
OODNIGHT, GRACIEGAY
OODNIGHT, GRACIEGAY
OODNIGHT, GRACIEGAY
(Cmd) set
prompt: (Cmd)
editor: gedit
echo: False
maxrepeats: 3
(Cmd) set maxrepeats 5
maxrepeats - was: 3
now: 5
(Cmd) say -ps --repeat=5 goodnight, Gracie
OODNIGHT, GRACIEGAY
OODNIGHT, GRACIEGAY
OODNIGHT, GRACIEGAY
OODNIGHT, GRACIEGAY
OODNIGHT, GRACIEGAY
(Cmd) hi
-------------------------[1]
help
-------------------------[2]
help say
-------------------------[3]
say goodnight, Gracie
-------------------------[4]
say -ps --repeat=5 goodnight, Gracie
-------------------------[5]
set
-------------------------[6]
set maxrepeats 5
-------------------------[7]
say -ps --repeat=5 goodnight, Gracie
(Cmd) run 4
say -ps --repeat=5 goodnight, Gracie
OODNIGHT, GRACIEGAY
OODNIGHT, GRACIEGAY
OODNIGHT, GRACIEGAY
OODNIGHT, GRACIEGAY
OODNIGHT, GRACIEGAY
(Cmd) orate Four score and
> seven releases ago
> our BDFL
> blah blah blah
>
>
Four score and seven releases ago our BDFL blah blah blah
(Cmd) & look, a shortcut!
look, a shortcut!
(Cmd) say put this in a file > myfile.txt
(Cmd) say < myfile.txt
put this in a file
(Cmd) set prompt "---> "
prompt - was: (Cmd)
now: --->
---> say goodbye
goodbye
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