Command Line Arguments

Advanced ~10 min read

The argparse module makes it easy to write user-friendly command-line interfaces. It parses the arguments defined in sys.argv.

Using argparse

You define what arguments your program requires, and argparse will figure out how to parse those out of sys.argv. It also automatically generates help and usage messages.

import argparse

# NOTE: This script is designed to be run from the command line
# Example: python prof-args.py --name Alice --age 30

def main():
    # Create the parser
    parser = argparse.ArgumentParser(description="A simple greeting script")

# Add arguments
    parser.add_argument("--name", type=str, help="Your name", required=True)
    parser.add_argument("--age", type=int, help="Your age", default=0)
    parser.add_argument("--verbose", action="store_true", help="Enable verbose output")

# Parse arguments (in a real script, you would just call parse_args())
    # Here we simulate arguments for demonstration since we are in a web environment
    # args = parser.parse_args() 
    
    # Simulating command line input: python script.py --name Alice --age 30 --verbose
    args = parser.parse_args(['--name', 'Alice', '--age', '30', '--verbose'])

if args.verbose:
        print("Verbose mode enabled")

print(f"Hello, {args.name}!")
    
    if args.age > 0:
        print(f"You are {args.age} years old.")

if __name__ == "__main__":
    main()

Output

Click Run to execute your code

Exercise: File Argument

Task: Create a parser that accepts a filename.

Requirements:

Add a --file argument.
Print "Processing file: [filename]".

Output

Click Run to execute your code

Show Solution

parser.add_argument("--file", required=True)
# ...
print(f"Processing file: {args.file}")

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Using argparse

Exercise: File Argument

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