Day 5: Python Basics for DevOps

_{Learning points:}

🔹 Python Fundamentals – Variables, data types, operators, and control flow.
🔹 Functions & Modules – Writing reusable functions and using built-in modules.
🔹 File Handling – Reading and writing files (open(), read(), write()).
🔹 Error Handling – Using try-except blocks to handle exceptions.
🔹 Working with Lists, Tuples, and Dictionaries – Data manipulation techniques.
🔹 Installing Packages with pip – Managing external libraries.
🔹 Basic Scripting for Automation – Writing and executing Python scripts.

LEARN:

Python tutorial by Sandip Das- Click Here

Initial Tasks:

✅ Task 1: Install Python (Check with python --version) and set up a virtual environment (venv).
✅ Task 2: Install VS Code or PyCharm for a better coding experience.
✅ Task 3: Write a simple Python script that prints "Hello, DevOps!".
✅ Task 4: Explore built-in data types (int, float, str, list, tuple, dict) and perform basic operations.
✅ Task 5: Write a Python function that takes two numbers as input and returns their sum.
✅ Task 6: Use Python’s os and sys modules to interact with the system.

Challenge 1: Create a Python program that accepts a user’s name as input and prints a greeting message.

Goal: Learn basic user input handling in Python.

Answer:

# Accept user input
name = input("Enter your name: ")

# Print a greeting message
print(f"Hello, {name}!")

Explanation of the Script:

• input("Enter your name: ") → Prompts the user for their name.

• print(f"Hello, {name}!") → Displays a greeting message.

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Challenge 2: Write a script that reads a text file and counts the number of words in it.

Goal: Learn file reading and text processing in Python.

Answer:

# Define the filename
filename = "sample.txt"

# Open the file and count words
with open(filename, "r") as file:
    words = file.read().split()

print(f"Word count: {len(words)}")

Explanation of the Script:

• open(filename, "r") → Opens the file in read mode.

• file.read().split() → Reads the content and splits it into words.

• len(words) → Counts the number of words.

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Challenge 3: Create a Python script that generates a random password of 12 characters.

Goal: Learn to generate random passwords.

Answer:

import random
import string

# Generate a random password
password = "".join(random.choices(string.ascii_letters + string.digits, k=12))

print(f"Generated password: {password}")

Explanation of the Script:

• random.choices() → Picks random characters from letters and digits.

• "".join(... ) → Joins selected characters into a single string.

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Challenge 4: Implement a Python program that checks if a number is prime.

Goal: Learn number theory and efficient prime checking.

Answer:

# Get user input
num = int(input("Enter a number: "))

# Check for prime
if num > 1 and all(num % i != 0 for i in range(2, int(num**0.5) + 1)):
    print(f"{num} is a prime number.")
else:
    print(f"{num} is not a prime number.")

Explanation of the Script:

• all(num % i != 0 for i in range(2, int(num**0.5) + 1)) → Efficiently checks divisibility up to square root of num.

• if num > 1 → Ensures numbers below 2 are not prime.

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Challenge 5: Write a script that reads a list of server names from a file and pings each one.

Goal: Learn network automation using Python.

Answer:

import os

# Read server names from a file and ping each
with open("servers.txt") as file:
    for server in file:
        os.system(f"ping -c 1 {server.strip()}")

Explanation of the Script:

• open("servers.txt") → Opens the file containing server names.

• os.system(f"ping -c 1 {server.strip()}") → Pings each server once.

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Challenge 6: Use the requests module to fetch and display data from a public API.

Goal: Learn to make API requests in Python.

Answer:

import requests

# Define the API URL
url = "https://jsonplaceholder.typicode.com/posts/1"

# Fetch data from the API
response = requests.get(url)

# Check if the request was successful
if response.status_code == 200:
    data = response.json()
    print("✅ Data fetched successfully:")
    print(data)
else:
    print(f"❌ Failed to fetch data. Status code: {response.status_code}")

Explanation of the Script:

• requests.get(url) → Sends a GET request to the API.

• response.status_code == 200 → Checks if the request was successful.

• response.json() → Converts the API response to a Python dictionary.

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Challenge 7: Automate a simple task using Python (Rename multiple files in a directory).

Goal: Learn file operations in Python.

Answer:

import os

# Define the target directory
directory = "files"

# Rename files in the directory
for i, filename in enumerate(os.listdir(directory), 1):
    old_path = os.path.join(directory, filename)
    new_path = os.path.join(directory, f"file_{i}.txt")

    os.rename(old_path, new_path)

print("✅ Files renamed successfully.")

Explanation of the Script:

• os.listdir(directory) → Lists all files in the specified directory.

• os.path.join(directory, filename) → Constructs full file paths.

• os.rename(old_path, new_path) → Renames files sequentially (e.g., file_1.txt, file_2.txt).

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Challenge 8: Create a Python script that monitors CPU and memory usage every 5 seconds.

Goal: Learn system monitoring in Python.

Answer:

import psutil
import time

# Monitor system resources
while True:
    cpu_usage = psutil.cpu_percent()
    memory_usage = psutil.virtual_memory().percent

    print(f"CPU Usage: {cpu_usage}% | Memory Usage: {memory_usage}%")

    time.sleep(5)  # Wait for 5 seconds before the next check

Explanation of the Script:

• psutil.cpu_percent() → Gets the current CPU usage percentage.

• psutil.virtual_memory().percent → Gets the memory (RAM) usage percentage.

• time.sleep(5) → Waits for 5 seconds before checking again.

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Challenge 9: Write a Python program that creates a user in Linux using subprocess and verifies the creation.

Goal: Learn to manage Linux users using Python.

Answer:

import subprocess

# Define the username
username = "testuser"

# Create a new user
subprocess.run(["sudo", "useradd", username])

# Verify the user creation
result = subprocess.run(["id", username], capture_output=True, text=True)

# Check if user exists
if result.returncode == 0:
    print(f"✅ User '{username}' created successfully.")
else:
    print(f"❌ Failed to create user '{username}'.")

Explanation of the Script:

• subprocess.run(["sudo", "useradd", username]) → Creates a new user using useradd (requires sudo).

• subprocess.run(["id", username], capture_output=True, text=True) → Checks if the user exists.

• result.returncode == 0 → If the command succeeds, the user was created successfully.