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Copy-ready Python snippets by topic and difficulty — short, focused, and runnable in the browser editor.
How to Kill Zombie Processes Matching a Name in Python
Scans running processes with ps, finds zombies whose command name matches a pattern, and attempts to kill them with SIGKILL.
import subprocess
import re
import signal
def find_zombies(name_pattern):
"""Find PIDs of zombie processes matching the given pattern."""
result = subprocess.run(["ps", "-eo", "pid,stat,comm"], capture_output=True, text=True)
zombies = []
for line in result.stdout.splitlines()[1:]: # Skip header
…How to Mock an Ansible Inventory in Python
Load an Ansible-style inventory JSON file into Python and simulate a playbook run across hosts and groups.
import json
from pathlib import Path
class InventoryMock:
def __init__(self, inventory_file: str):
self.inventory_file = Path(inventory_file)
self.hosts = {}
def load(self):
if not self.inventory_file.exists():
raise FileNotFoundError(f"Inventory file {self.inventory_file…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 Ping Multiple Hosts in Parallel with Python ThreadPoolExecutor
A parallel host-pinging script using ThreadPoolExecutor and subprocess to check connectivity across multiple addresses concurrently.
import subprocess
from concurrent.futures import ThreadPoolExecutor
from pathlib import Path
HOSTS = [
"google.com",
"github.com",
"stackoverflow.com",
"nonexistent.invalid",
"localhost",
]
def ping_host(host: str) -> str:
"""Ping a single host and return a status string."""
result = subp…How to Scan Open Ports on a Host with Python
A Python function that uses socket.connect_ex to check for open TCP ports on a given host within a range and returns a list of open ports.
import socket
def scan_ports(host, start_port, end_port):
open_ports = []
for port in range(start_port, end_port + 1):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.settimeout(0.5)
result = sock.connect_ex((host, port))
if result == 0:
open_ports.app…How to Send an Email with smtplib and a Mock Server in Python
Send an email using smtplib and verify it with a local aiosmtpd mock SMTP server — perfect for testing without a real mail server.
import smtplib
from email.message import EmailMessage
import aiosmtpd.controller as controller
import threading
def handle_message(server, session, envelope):
print(f"Mock server received message:")
print(f"From: {envelope.mail_from}")
print(f"To: {envelope.rcpt_tos}")
print(f"Subject: {envelope.cont…How to Track GitHub Stars, Forks, and Watchers in Python
Automatically fetch and track stars, forks, and watchers for multiple GitHub repositories, saving snapshots locally as JSON files for historical analysis.
import os
import time
import json
import requests
from pathlib import Path
from datetime import datetime
REPOS = [
"psf/requests",
"python/cpython",
"pallets/flask",
]
DATA_DIR = Path("github_metrics")
def fetch_repo_stats(repo):
url = f"https://api.github.com/repos/{repo}"
resp = requests.get(ur…How to Update a Hosts File to Block Distractions in Python
This script updates a local hosts file (or a demo file) by adding or updating entries to block distracting websites like Facebook and Twitter.
from pathlib import Path
def update_hosts(entries):
"""
Add or update blocking entries in the hosts file.
Uses a local demo file by default to avoid system changes.
"""
hosts_path = Path("demo_hosts.txt")
# Create demo file if it doesn't exist
if not hosts_path.exists():
hosts…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 automatically organize your Downloads folder by file type in Python
This script scans the Downloads folder and moves files into sub-folders based on their extensions (e.g., Images, Documents, Videos).
import os
import shutil
from pathlib import Path
def organize_downloads_folder(downloads_path=None):
if downloads_path is None:
downloads_path = str(Path.home() / "Downloads")
if not os.path.exists(downloads_path):
print(f"Path {downloads_path} does not exist.")
return
fi…Parse nginx access log top IPs in Python
Reads an nginx access log line by line, extracts the client IP, and returns the most frequent IPs using a regex and Counter.
import re
from collections import Counter
def top_ips(log_file, n=10):
ip_pattern = re.compile(r'^(\S+)')
ip_counts = Counter()
with open(log_file, 'r') as f:
for line in f:
match = ip_pattern.match(line)
if match:
ip_counts[match.group(1)] += 1
return…Port Scan Localhost Common Ports in Python
Scan common localhost ports (HTTP, HTTPS, SSH, FTP, and more) with a fast socket-based Python script that prints an open/closed status table.
import socket
from datetime import datetime
COMMON_PORTS = {
80: "HTTP",
443: "HTTPS",
22: "SSH",
21: "FTP",
25: "SMTP",
3306: "MySQL",
5432: "PostgreSQL"
}
def scan_port(port):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.settimeout(0.1)
try:
resu…Post a message to a Slack webhook in Python
Send a message to a Slack webhook endpoint using the standard library's urllib.request, handling the POST request and response cleanly.
import json
from urllib import request
def post_to_slack(webhook_url: str, message: str) -> dict:
payload = json.dumps({"text": message}).encode("utf-8")
req = request.Request(
webhook_url,
data=payload,
headers={"Content-Type": "application/json"},
method="POST",
)
wit…Restore sqlite from latest backup file in Python
This script finds the most recently modified backup file in a directory and restores it to the main database path, then verifies the restored data.
import sqlite3
import glob
import os
import shutil
def restore_latest_backup(db_path, backup_dir):
backups = sorted(glob.glob(os.path.join(backup_dir, "*.db")), key=os.path.getmtime)
if not backups:
raise FileNotFoundError("No backup files found")
latest = backups[-1]
shutil.copy2(latest, db_p…Stress CPU Threads with a Mock Compute in Python
Simulates CPU-intensive work across multiple threads to test how Python schedules parallel compute.
import threading
import time
def stress_cpu(iterations: int):
result = 0
for i in range(iterations):
result += i * i % 1000
return result
def run_mock_stress(thread_count: int, iterations: int):
threads = []
for tid in range(thread_count):
t = threading.Thread(target=lambda: str…Track Internet Connectivity and Downtime Automatically in Python
Monitors internet connectivity by pinging a remote host and logs any downtime events with timestamps and duration.
import time
import subprocess
from datetime import datetime
def check_internet(host="8.8.8.8", timeout=3):
"""Returns True if internet is reachable via ping."""
try:
subprocess.run(
["ping", "-c", "1", "-W", str(timeout), host],
capture_output=True,
timeout=timeout …Build a Python Utility That Detects Duplicate Records Across Multiple Excel Sheets
A Python utility that uses pandas to find overlapping records across different Excel sheets based on specified key columns.
import pandas as pd
from pathlib import Path
def find_duplicate_records_across_sheets(file_path: str, key_columns: list, sheet_names: list) -> dict:
"""
Detect duplicate records across multiple Excel sheets based on specified key columns.
Args:
file_path: Path to the Excel file
key_co…Fan Out Records to Multiple Sinks in Python
Distribute the same records across multiple target sinks (database, API, queue, etc.) using a defaultdict-based fan-out pattern.
import json
from collections import defaultdict
SINKS = ["database", "api", "message_queue", "data_lake", "monitoring"]
def fan_out(records, *sinks):
dist = defaultdict(list)
for record in records:
for sink in sinks:
dist[sink].append(record)
return dict(dist)
if __name__ == "__main_…How to Find Missing Values in Large Datasets in Python
Analyze missing values across multiple large pandas DataFrames with counts and percentages.
import pandas as pd
import numpy as np
def find_missing_values_summary(datasets):
"""Analyze missing values across multiple datasets (dict of name: DataFrame)."""
summary = {}
for name, df in datasets.items():
missing_count = df.isnull().sum()
total_rows = len(df)
missing_pct = (mi…How to Implement Slowly Changing Dimension Type 2 History in Python
Build a type-2 slowly changing dimension pipeline that closes old records and opens new ones when customer data changes.
from datetime import datetime, timedelta
def apply_scd_type2(records, current_date):
"""Returns active records after inserting new records with type-2 history."""
history = []
active = {}
for record in records:
key = record["customer_id"]
if key in active:
active[key]["end…How to Implement a Sliding Window Average in Python
Compute the average of the most recent N values in a stream using a bounded deque, efficiently updating the total as new values arrive.
from collections import deque
class SlidingWindowAverage:
def __init__(self, window_size):
self.window_size = window_size
self.window = deque(maxlen=window_size)
self.total = 0
def add(self, value):
if len(self.window) == self.window_size:
self.total -= self.windo…How to Validate Data in a Python Pipeline
A helper module to validate common record types — email, positive integer, and non-empty string list — before processing data in a pipeline.
from typing import Any, Iterable
def is_valid_email(email: str) -> bool:
"""Basic email check: one '@', no spaces, dot after '@'."""
if "@" not in email or " " in email:
return False
local, _, domain = email.partition("@")
return bool(local) and "." in domain
def is_positive_int(value: Any)…Map Partition Over Chunks in Python with Multiprocessing and Mock
Process data in chunks across multiple CPU cores using multiprocessing Pool.map, and mock the chunk function to test partitioning behavior without heavy computation.
from multiprocessing import Pool
from unittest.mock import patch, Mock
def process_chunk(chunk):
return [x * x for x in chunk]
def map_partition_over_chunks(data, chunk_size, process_func=process_chunk):
chunks = [data[i:i + chunk_size] for i in range(0, len(data), chunk_size)]
with Pool() as pool:
…Pipeline stage compose functions left to right in Python
Compose multiple functions into a left-to-right pipeline so each stage receives the output of the previous one.
def compose(*funcs):
"""Compose functions left to right: compose(f, g, h)(x) == h(g(f(x)))"""
def composed(arg):
result = arg
for func in funcs:
result = func(result)
return result
return composed
if __name__ == "__main__":
def add_one(x):
return x + 1
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