System Administration Scripts

The Admin's Swiss Army Knife

Python is the perfect language for system glue code. It replaces complex shell scripts with readable, maintainable logic.

System Monitoring (psutil)

psutil provides cross-platform info on CPU, memory, disks, and network.

import psutil

# CPU Usage
print(f"CPU: {psutil.cpu_percent()}%")

# Memory Usage
mem = psutil.virtual_memory()
print(f"Memory: {mem.percent}%")

# Disk Usage
disk = psutil.disk_usage('/')
print(f"Disk Space: {disk.percent}%")

Executing Commands (subprocess)

Use subprocess.run to call external binaries safely.

import subprocess

# Run a command and get output
res = subprocess.run(['ls', '-la'], capture_output=True, text=True)
print(res.stdout)

Automated Backups

import shutil
from datetime import datetime

timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
shutil.make_archive(f"backup_{timestamp}", 'zip', '/path/to/source')

Log Parsing

Combine re (regex) with file I/O to extract insights from logs.

import re

error_pattern = re.compile(r"ERROR|CRITICAL")

with open("app.log", "r") as f:
errors = [line for line in f if error_pattern.search(line)]

print(f"Found {len(errors)} critical lines.")

✅ Practice (30 minutes)

Write a script that monitors CPU and sends an email if it stays above 90% for 1 minute.
Create a cleanup script that deletes files older than 30 days in a specific folder.
Parse a web server log and count the number of 404 errors.
Schedule your Python script using crontab (Linux) or Task Scheduler (Windows).