3

There has been a need for python command line utilities at work lately and I have no experience in writing cli's. Regardless, I must still pop them out.

My biggest hurdle is the structure of these programs. Also, the method in getting and verifying input from the user. I have been ending up with very looong while loops and I just dont think that is the most efficient approach.

Could someone provide links to open source cli programs that I may pick to gain a bit of an understanding? Or, books, tutorials, etc that I could get my hands on. I have dug around but have had little success (my google skills must be lacking).

Improve this question

4 Answers 4

Reset to default
5

I like baker. You use it like so:

% cat my.py
import baker


@baker.command
def cmd(start, end):
    print '%s %s' % (start, end)


if __name__ == '__main__':
    baker.run()

% python my.py cmd 2010-12-01 2010-12-31
2010-12-01 2010-12-31
Improve this answer
Sign up to request clarification or add additional context in comments.

Comments

4

Random hints:

  • the optionparser module is good for parsing complex options
  • many python modules indeed are cli programs. See there (for example, see python2.6/json/tool.py which you can run with python -m json.tool)

It is a good idea to use

 def main(arguments):
     etc.

 if __name__ == '__main__':
     # only if we are executed rather than imported as a module:
     import sys
     main(sys.argv)

Such that the parts of yor app can be reused by simply importing them

Improve this answer

1 Comment

Optionparser is an entry point to most of my code. I had never considered importing right before main() gets called to cut down on wasted imports.
0

Pretty much any python script can be a "command line program". What specific question do you have?

Improve this answer

3 Comments

One example is curl. it has a slew of options, flags, etc. What is a good method at storing these and deciding the program flow from them? Like would I just have a bunch of stored variables that execute methods from if-else logic in main(). Or is there a sort of 'standard' to handling this scenario.
Another example is say I have two databases from which I want to compare entries. The User would be prompted 'if' there are any differences as to what to do. He could keep, delete, or change the values. The issue is that he must be presented the differences, must provide input, and the input must be validated. The process can become extensive. So do you know of open-source programs I could pick through that are similar in the scope of this example?
Those are really specific questions. You should keep your questions to such a scope that they're answerable.
0

If you can use python 2.7 or 3, or expect a common environment from which it might be accessible, consider argparse instead of optparse. It gives you the same control optparse does over options with arguments.

I personally don't mind putting the all the parsing in the if __name__ == '__main__' block if it's pretty straightforward.

In your comment to Falmarri's response, you mention extensive user interaction during use of your CLI program - for me, that's starting to edge towards a "line-oriented command interpreter" like the cmd in the standard libary, or the excellent cmd2. Looping over lines that are different with manually parsed raw_input's is replicating some of the functionality you could get from one of these. I'd also be interested to see good examples of what you describe.

Improve this answer

Comments

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.