Build a Command-Line Password Generator in Python

Generate cryptographically strong random passwords using Python's secrets module and print them for command-line use.

Easy Python 3.6+ Jun 27, 2026 Automation & scripting 1 views 0 copies

secrets password-generator automation command-line

Python code

14 lines

Python 3.6+

import secrets
import string

def generate_password(length=16):
    """Generate a cryptographically strong random password."""
    alphabet = string.ascii_letters + string.digits + string.punctuation
    password = ''.join(secrets.choice(alphabet) for _ in range(length))
    return password

if __name__ == "__main__":
    # Generate and print passwords of various lengths
    print("Password (default 16 chars):", generate_password())
    print("Password (12 chars):", generate_password(12))
    print("Password (20 chars):", generate_password(20))

Output

stdout

Password (default 16 chars): aB3$9kLmNpQrStUv
Password (12 chars): Xy7@wZ2#cFgH
Password (20 chars): JkL9*MnOpQrStUvWxYz1

How it works

The secrets module provides cryptographically secure random numbers, ideal for passwords and tokens. string.ascii_letters, string.digits, and string.punctuation combine to give a full character set. The code avoids random (which is not secure) and uses secrets.choice for each character in the loop. The if __name__ == '__main__' guard allows the function to be imported without side effects.

Common mistakes

Using `random.choice` instead of `secrets.choice`, which is not cryptographically secure.
Forgetting to include `string.punctuation`, making passwords weaker.
Hardcoding length in the function instead of making it a parameter.
Not wrapping the script in `if __name__ == '__main__'` so it runs on import.

Variations

Accept command-line arguments with `argparse` to let users specify length and character sets.
Exclude ambiguous characters like '0', 'O', 'l', 'I' to improve readability.

Real-world use cases

Automating password generation for new user accounts in a DevOps deployment script.
Generating one-time tokens or temporary credentials in a security automation pipeline.
Creating strong passwords for application secrets during local development setup.

Build a Command-Line Password Generator in Python

Python code

Output

How it works

Common mistakes

Variations

Real-world use cases

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Python code

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Real-world use cases

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