Python Intermediate Lesson 9: Command-Line Tools With argparse

📎 This article includes 3 downloadable practice files ↓

📘 Python Intermediate Course · Lesson 9 of 10

Instead of editing the script every time someone wants a different filter, give it options:

python sales.py --status Overdue
python sales.py --rep Neha --month 2026-07
python sales.py --help

import argparse
ap = argparse.ArgumentParser(description="Sales totals from sales.csv")
ap.add_argument("--status", choices=["Paid", "Pending", "Overdue"])
ap.add_argument("--rep")
ap.add_argument("--month", help="YYYY-MM")
a = ap.parse_args()
if a.status: rows = [r for r in rows if r["status"] == a.status]

argparse writes the --help text and rejects invalid choices with a clear message, for free.

Run it on a schedule

1. Make run-report.bat: cd /d D:\sales-report && .venv\Scripts\python.exe report.py --month %1 >> log.txt 2>&1
2. Task Scheduler > Create Basic Task > Monthly > Start a program > the .bat file.
3. Tick “Run whether user is logged on or not” for unattended runs.

Practice

Unzip the practice data into a folder, put this lesson’s script in the same folder and run it (python pyi-NN.py). Compare with the expected output file. Then change one thing (a filter, a column, a format) and predict the new output before you run it.