Making a CLI Tool with argparse

Photo by Immo Wegmann on Unsplash

Hey there! Pretty cool, huh? You ever wonder about this? ever wanted to build your own command line interface (cli) tool but didn't know where to start?

Well, you're in the right place! Pretty cool, huh? You ever wonder about this? today, we'll explore how to use python's argparse module to make a handy cli tool. It's easier than you think, and by the end of this post, you'll have all the knowledge you need to create your own.

What is argparse?

argparse is a Python module that makes it easy to write user-friendly command-line interfaces. Pretty cool, huh?

The program defines what arguments it requires, and argparse figures out how to parse those out of sys.argv.

The argparse module also automatically generates help and usage messages and issues errors when users give the program invalid arguments.

Getting Started with argparse

First things first, let's see how we can set up a basic script using argparse. Pretty cool, huh? We'll create a simple CLI tool that greets the user by name. Pretty cool, huh? Here's how you can do it:

Source: based on community trends from Reddit and YouTube

Copyable Code Example


import argparse

def greet(args):
    print(f"Hello, {args.name}! How are you today?")

def main():
    parser = argparse.ArgumentParser(description="Greet the user.")
    parser.add_argument("name", type=str, help="The name of the user to greet.")
    args = parser.parse_args()
    greet(args)

if __name__ == "__main__":
    main()
    

    In the code above, we first import the argparse module. We then define a function greet which simply prints a greeting message. The main function sets up an argument parser, adds a positional argument name, and finally, calls the greet function with the parsed arguments.
    
    Running Your CLI Tool
    To run your new CLI tool, you'd typically use the command line. Assuming you've saved your script as greet.py, you can run it like this:

    
python greet.py Alice
    

    And voilà! You should see the output: Hello, Alice! How are you today?

    Adding More Functionality
    Let's say you want to make the greeting more personal by adding an option to include the time of day in your greeting. Here’s how you could update your function:

    
import argparse

def greet(args):
    greeting = f"Hello, {args.name}!"
    if args.time:
        greeting += f" Good {args.time}!"
    print(greeting + " How are you today?")

def main():
    parser = argparse.ArgumentParser(description="Greet the user.")
    parser.add_argument("name", type=str, help="The name of the user to greet.")
    parser.add_argument("--time", type=str, help="The time of day to include in the greeting.", choices=['morning', 'afternoon', 'evening'])
    args = parser.parse_args()
    greet(args)

if __name__ == "__main__":
    main()
    

    Here, we added an optional argument --time that lets the user specify the time of day, which gets included in the greeting. This makes your CLI tool even more dynamic and user-friendly!

    Wrapping Up
    And there you have it! You've just created a simple yet fully functional CLI tool using Python's argparse module. The beauty of argparse is in its simplicity and in how it handles much of the heavy lifting for you, making your code cleaner and more maintainable. Feel free to experiment with more complex arguments and even sub-commands. The possibilities are limitless! Happy coding!

Making a CLI Tool with argparse