Why cmd2


cmd is the Python Standard Library’s module for creating simple interactive command-line applications. cmd is an extremely bare-bones framework which leaves a lot to be desired. It doesn’t even include a built-in way to exit from an application!

Since the API provided by cmd provides the foundation on which cmd2 is based, understanding the use of cmd is the first step in learning the use of cmd2. Once you have read the cmd docs, return here to learn the ways that cmd2 differs from cmd.


cmd2 is a batteries-included extension of cmd, which provides a wealth of functionality to make it quicker and easier for developers to create feature-rich interactive command-line applications which delight customers.

cmd2 can be used as a drop-in replacement for cmd with a few minor discrepancies as discussed in the Incompatibilities section. Simply importing cmd2 in place of cmd will add many features to an application without any further modifications. Migrating to cmd2 will also open many additional doors for making it possible for developers to provide a top-notch interactive command-line experience for their users.

Free Features

After switching from cmd to cmd2, your application will have the following new features and capabilities, without you having to do anything:

  • More robust History. Both cmd and cmd2 have readline history, but cmd2 also has a robust history command which allows you to edit prior commands in a text editor of your choosing, re-run multiple commands at a time, and save prior commands as a script to be executed later.
  • Users can redirect output to a file or pipe it to some other operating system command. You did remember to use self.stdout instead of sys.stdout in all of your print functions, right? If you did, then this will work out of the box. If you didn’t, you’ll have to go back and fix them. Before you do, you might consider the various ways cmd2 has of Generating Output.
  • Users can load script files, which contain a series of commands to be executed.
  • Users can create Shortcuts, Aliases, and Macros to reduce the typing required for repetitive commands.
  • Embedded python shell allows a user to execute python code from within your cmd2 app. How meta.
  • Clipboard Integration allows you to save command output to the operating system clipboard.
  • A built-in Timer can show how long it takes a command to execute
  • A Transcript is a file which contains both the input and output of a successful session of a cmd2-based app. The transcript can be played back into the app as a unit test.

Next Steps

In addition to the features you get with no additional work, cmd2 offers a broad range of additional capabilties which can be easily added to your application. Next Steps has some ideas of where you can start, or you can dig in to all the Features.