AdvancedCross-Platform

Lab: cross-platform

Apply path portability, platform-specific branching, and script execution decisions.

Lab · optionalUtilitiesAdvanced9 min

Recommended first

Shebang and executables

By the end of this lesson you will be able to:

Construct paths portably using pathlib instead of string concatenation
Choose the right platform detection strategy for a situation
Write a shebang that works across typical Unix installations
Diagnose a portability failure from its symptoms

Optional scenario lab. Cross-platform issues are often subtle — the same code behaves differently on macOS, Linux, and Windows in ways that don't appear until a user files a bug. Practice the decisions here.

Scenarios: cross-platform utilities

1.
You need to join a base directory path with a filename in Python. Most portable approach?
base + "/" + filenameos.path.join(base, filename)pathlib.Path(base) / filenamef"{base}\\{filename}"
2.
Your CLI needs to open a browser. The command is open on macOS, xdg-open on Linux, and start on Windows. Best approach?
Hardcode `open` — most users are on macOSUse Python's webbrowser.open() which handles the platform differenceCheck sys.platform and branch to the right commandBoth B and C are valid
3.
You want a Python script to be executable with ./myscript.py on any Unix-like system. Which shebang is most portable?
#!/usr/bin/python3#!/usr/local/bin/python3#!/usr/bin/env python3#!/bin/python
4.
A Python module named Utils.py can be imported as import utils on macOS but fails on Linux. The root cause is filesystem case sensitivity.
TrueFalse
5.
Your CLI stores user configuration. Where should the config file live for proper cross-platform behavior?
~/.myapp/config.json on all platformsThe directory the script was run fromThe OS-appropriate config directory via platformdirs or click.get_app_dir()/etc/myapp/config.json

The cross-platform mindset: use the platform's abstractions (pathlib, webbrowser, platformdirs) rather than hard-coding OS assumptions. Test on at least two platforms before calling something portable.

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Shebang and executables

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