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How to Mock FFmpeg subprocess Calls in Python
Compress a video with ffmpeg while mocking subprocess.run to test the command construction without executing the actual encoder.
import subprocess
from unittest.mock import Mock, patch
def compress_video(input_path: str, output_path: str, crf: int = 23) -> None:
"""Compress a video using ffmpeg with a given CRF (quality) value."""
command = [
"ffmpeg",
"-i", input_path,
"-c:v", "libx264",
"-crf", str(cr…How to Mock a Whisper API Transcription Stub in Python
Simulate an OpenAI Whisper-style transcription response with a dataclass request model and a mock function that returns structured audio transcription output.
import json
from dataclasses import dataclass
from typing import Optional
@dataclass
class AudioRequest:
file_path: str
language: Optional[str] = None
def to_api_payload(self) -> dict:
return {"file": self.file_path, "language": self.language}
def mock_whisper_transcribe(payload: dict) -> dict:
…How to Monitor Process RSS Memory in Python
Poll the VmRSS field from /proc/PID/status to watch a process's resident memory and alert on growth.
import os
import time
import subprocess
import sys
def get_rss_mb(pid):
"""Return RSS memory in MB for a given process ID."""
try:
with open(f"/proc/{pid}/status", "r") as f:
for line in f:
if line.startswith("VmRSS:"):
return int(line.split()[1]) / 1024…How to Parse CLI Arguments in Python with argparse
Build a beginner-friendly CLI with argparse that accepts optional --name, --greeting, and --uppercase flags, then prints a customizable greeting.
import argparse
def main():
parser = argparse.ArgumentParser(description="Greet a user with optional customization.")
parser.add_argument("--name", default="world", help="Name to greet")
parser.add_argument("--greeting", default="Hello", help="Greeting word")
parser.add_argument("--uppercase", action=…How to Parse Terraform Plan Output in Python
Parse mock Terraform plan output text into structured add, change, and destroy lists using Python.
import json
from typing import Dict, List
def parse_terraform_plan_output(plan_output_text: str) -> Dict[str, List[str]]:
"""
Parses a mock Terraform plan output text into a structured dictionary.
"""
parsed: Dict[str, List[str]] = {"add": [], "change": [], "destroy": []}
for line in plan_output_…How to Perform a DNS Lookup for A Records in Python
Resolve a hostname to IPv4 A records using Python's built-in socket.getaddrinfo and return a sorted list of addresses.
import socket
def get_a_records(hostname):
"""Fetch A records (IPv4 addresses) for a given hostname."""
try:
# getaddrinfo with family AF_INET restricts to IPv4 (A records)
infos = socket.getaddrinfo(hostname, None, socket.AF_INET)
# Each info tuple: (family, type, proto, canonname, so…How to Recover Deleted .txt Files from a Backup in Python
A Python function that searches a backup directory recursively and copies all .txt files to a destination folder, printing each recovered file name and a total count.
import os
import shutil
from pathlib import Path
def recover_deleted_txt_files(source_backup_dir: str, destination_dir: str) -> None:
"""Recover .txt files from backup directory."""
backup_path = Path(source_backup_dir)
dest_path = Path(destination_dir)
dest_path.mkdir(parents=True, exist_ok=True)
…How to Resize Hundreds of Images in Batch with Python
Resize every image in a folder to a target size using Pillow, creating a new subfolder for processed files.
import os
from PIL import Image
def resize_images_in_batch(directory, output_size=(800, 600)):
if not os.path.exists(directory):
print(f"Directory {directory} does not exist.")
return
output_dir = os.path.join(directory, "resized")
os.makedirs(output_dir, exist_ok=True)
for filename in…How to Save a VM Snapshot State to a JSON File in Python
Define a dataclass for a VM snapshot and serialize it to a JSON file, then reload it to verify the state.
import json
from dataclasses import dataclass, asdict
from pathlib import Path
@dataclass
class VMSnapshot:
name: str
memory_mb: int
disk_gb: int
state: str = "saved"
def snapshot_to_file(self, path: Path) -> str:
"""Write snapshot state to a JSON file and return the filename."""
…How to Scan Files Against a Malware Hash List in Python
Compare a file's SHA-256 hash against a known malware hash set and report whether it's clean or infected.
import hashlib
from pathlib import Path
# Mock file content (in real usage, read from disk)
MOCK_FILE_CONTENT = b"print('hello world')"
KNOWN_MALWARE_HASHES = {
"8d969eef6ecad3c29a3a629280e686cf0c3f5d5a86aff3ca12020c923adc6c92",
"5e884898da28047151d0e56f8dc6292773603d0d6aabbdd62a11ef721d1542d8",
}
def sha25…How to Simulate a Traceroute in Python
This Python script simulates a network traceroute by generating mock hop IPs, random delays, and a destination reach condition, useful for testing network scripts.
import random
import time
def simulate_traceroute(destination, max_hops=30):
"""Simulate a traceroute to a destination with mock hop delays."""
print(f"Traceroute to {destination} ({max_hops} hops max):")
for hop in range(1, max_hops + 1):
# Mock IP address for the hop
mock_ip = f"10.0.{ra…How to Sort Command-Line Arguments in Python
Build a beginner-friendly argparse CLI that sorts numbers or words passed as arguments, with an optional reverse flag.
import argparse
def main():
parser = argparse.ArgumentParser(description="Sort numbers or words from the command line.")
parser.add_argument("items", nargs="+", help="Items to sort (numbers or words)")
parser.add_argument("--reverse", "-r", action="store_true", help="Sort in descending order")
args =…How to Split PDF Pages into Ranges in Python
Simulates splitting a PDF into page ranges by validating and returning structured range splits for automation workflows.
import os
def split_pdf_ranges(pdf_name, num_pages, ranges):
"""
Simulates splitting a PDF by returning the page ranges that would be split.
Args:
pdf_name (str): Name of the PDF file.
num_pages (int): Total number of pages in the PDF.
ranges (list of tuple): List of (start, end) …How to Strip EXIF Metadata from Images in Python
Remove EXIF metadata from image bytes using Pillow, with a mock JPEG generator for testing.
from PIL import Image
from PIL.ExifTags import TAGS
from io import BytesIO
import struct
def strip_exif(image_bytes, remove_metadata=True):
"""Remove EXIF metadata from image bytes."""
img = Image.open(BytesIO(image_bytes))
if remove_metadata:
# Clear all metadata
img.info.clear()
# Sa…How to Tail and Colorize Error Lines in Python
Reads the last N lines of a log file and prints error lines in red using ANSI color codes.
import sys
import time
from pathlib import Path
def tail_colorize(filename: str, lines: int = 20) -> None:
"""Read last N lines of a file, printing errors in red."""
path = Path(filename)
if not path.exists():
print(f"File '{filename}' not found.", file=sys.stderr)
return
# Read last …How to Watch a Folder and Convert New Images in Python
Watch a folder for new files and mock-convert images by copying and renaming them in an output directory.
import time
import hashlib
from pathlib import Path
from datetime import datetime
def mock_convert_image(source: Path, dest_dir: Path) -> Path:
"""Mock image conversion: copy bytes and add .converted suffix."""
dest = dest_dir / f"{source.stem}.converted{source.suffix}"
dest.write_bytes(source.read_bytes(…How to Write an IP Block List to hosts.deny in Python
This Python script validates a list of IP addresses and CIDR ranges, then writes them to a hosts.deny file to block connections at the TCP wrapper level.
from ipaddress import ip_network
def write_hosts_deny(ip_list, output_file="hosts.deny"):
with open(output_file, "w") as f:
for ip in ip_list:
try:
ip_network(ip)
f.write(f"ALL: {ip}\n")
except ValueError:
continue
print(f"Written…How to generate an htpasswd bcrypt entry in Python
Create a mock htpasswd file entry with a bcrypt-hashed password for a given username using a simple Python script.
import bcrypt
def mock_htpasswd_entry(username, password):
salt = bcrypt.gensalt(rounds=12)
hashed = bcrypt.hashpw(password.encode(), salt).decode()
return f"{username}:{hashed}"
if __name__ == "__main__":
entry = mock_htpasswd_entry("demo_user", "s3cretP@ss")
print(entry)How to generate website performance reports from HTTP requests in Python
Measure and report website load time, status code, and content size using Python's standard library.
import urllib.request
import time
def measure_website_load_time(url):
"""Measures total loading time of a website."""
start_time = time.time()
try:
with urllib.request.urlopen(url, timeout=10) as response:
content = response.read()
status_code = response.status
…How to rename music files by ID3 tags in Python
Renames MP3 files in a folder using artist and title extracted from ID3 tags, with a mock fallback that parses filenames.
import os
import re
from pathlib import Path
def sanitize_filename(name: str) -> str:
return re.sub(r'[<>:"/\\|?*]', '_', name).strip()
def rename_mp3_from_id3(path: Path) -> None:
for f in path.glob("*.mp3"):
# Mock ID3 extraction: derive artist/title from filename
stem = f.stem
if "…How to validate argparse CLI commands in Python
Build a beginner-friendly command-line argument parser with argparse, including required and optional arguments, plus simple validation for age.
import argparse
def main():
parser = argparse.ArgumentParser(description="Validate CLI arguments for beginners.")
parser.add_argument("name", type=str, help="Your name.")
parser.add_argument("--age", type=int, default=None, help="Your age (optional).")
parser.add_argument("--verbose", action="store_t…Mock Certbot Renewal in Python for Testing
Simulates a Let's Encrypt certificate renewal by writing a mock certificate file and printing realistic certbot CLI output, without calling the actual certbot.
import subprocess
import sys
from datetime import datetime, timedelta
from pathlib import Path
def renew_cert(domain: str, output_dir: str = "certs") -> str:
"""Simulate a Let's Encrypt renewal with mock certbot output."""
out = Path(output_dir)
out.mkdir(parents=True, exist_ok=True)
cert_path = out…Mock a Helm Upgrade Install Command in Python
Use unittest mock to simulate a Helm upgrade --install call for testing automation scripts without a real cluster.
from unittest.mock import MagicMock, patch
class HelmClient:
def upgrade_install(self, release, chart, namespace="default"):
# Simulates the helm upgrade --install command
return f"Release {release} upgraded/installed in {namespace} using chart {chart}"
@patch("helm_client.HelmClient.upgrade_in…Mock systemctl Wrapper in Python for Service Testing
A Python class-based mock of systemctl that simulates start, stop, restart, and status operations for a service, useful for testing automation scripts.
import subprocess
import sys
class ServiceManager:
def __init__(self, service_name):
self.service_name = service_name
self.status = "inactive"
def start(self):
self.status = "active"
print(f"Starting {self.service_name}... OK")
def stop(self):
self.status …Browse by section
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