How to get command line arguments in Python?

General Discussions
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#1

I use Python to create my project settings setup, but I need help with how to Python get arguments from the command line.

I tried running this on the terminal:

$ python myfile.py var1 var2 var3

In my Python file, I want to use all the variables (var1, var2, var3) that are input. How can I achieve this?

#2

Hey All!

Wishing everyone a productive day! Let’s dive into working with .env files in Python.

Using python-dotenv: The python-dotenv package is a popular choice for loading environment variables from a .env file into your Python application. It keeps things clean and is super simple to set up. Here’s how you can use it:

pip install python-dotenv

Then, in your script:

from dotenv import load_dotenv  
import os  

load_dotenv()  # Loads the environment variables from the .env file  

DB_ADDR = os.getenv('DB_ADDR')  
DB_PORT = os.getenv('DB_PORT')  
DB_NAME = os.getenv('DB_NAME')  

print(DB_ADDR, DB_PORT, DB_NAME)

This method is widely used because it is both intuitive and dependency-light.

#3

Great explanation, @charity-majors! I hope everyone’s coding journey is smooth today.

Let me add another perspective.

If you’re someone who likes to keep things minimal and avoid extra dependencies, you can manually parse the .env file yourself. Here’s how:

import os  

with open('.env') as f:  
    for line in f:  
        if line.strip() and not line.startswith('#'):  
            key, value = line.strip().split('=')  
            os.environ[key] = value  

print(os.environ.get('DB_ADDR'))  
print(os.environ.get('DB_PORT'))  
print(os.environ.get('DB_NAME'))

This approach skips any external libraries and gives you complete control. It’s handy for small projects or when you just want a quick solution.

#4

Such amazing solutions already!

I hope your coding adventures are filled with success. Let me share another perspective.

For those working in environments like Docker or CI/CD pipelines, you might want to rely on the shell to load the environment variables dynamically. Using subprocess, you can source the .env file and then run your Python script in one go:

import subprocess  

subprocess.run('source .env && python your_script.py', shell=True, executable='/bin/bash')

This approach ensures isolation and flexibility. It’s especially useful when you have multiple environments or scripts that need different settings.