Скачать или смотреть Resolving the No module named psutil Error in Python Scripts

Learn how to fix the `No module named psutil` error when executing Python scripts without the shebang line!
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This video is based on the question https://stackoverflow.com/q/63303077/ asked by the user 'Shambhav Agrawal' ( https://stackoverflow.com/u/11708288/ ) and on the answer https://stackoverflow.com/a/63303135/ provided by the user 'Derlin' ( https://stackoverflow.com/u/2667536/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the No module named psutil Error

If you've ever encountered the "No module named psutil" error while running your Python script and wondered why it works perfectly when invoked with a shebang and chmod, you're not alone. This is a common issue faced by many Python developers, particularly when transitioning between different ways of executing their scripts.

Let’s break down the problem, and then we will walk through the solution in a structured manner.

The Problem

You have a Python script called health.py that uses the psutil library to check disk usage. When you execute your script in the terminal using the command:

[[See Video to Reveal this Text or Code Snippet]]

You see the following error:

[[See Video to Reveal this Text or Code Snippet]]

However, when you make your script executable and run it with:

[[See Video to Reveal this Text or Code Snippet]]

it executes without any issues, returning a disk usage value!

Why Does This Happen?

The difference in the execution method is the crux of the issue. Let’s explore this in detail.

Shebang Explanation

The first line of your script, known as the shebang, is:

[[See Video to Reveal this Text or Code Snippet]]

This line tells the system to use python3 to execute the script regardless of what the default Python interpreter is when simply using the python command.

Python Environment Discrepancy

When you execute python health.py, it is likely using Python 2.x if that's what your python command is symlinked to. This can create conflicts, especially if the psutil module is installed for Python 3 but not for Python 2.

How to Check Your Python Version

To verify which Python version is being used, type the following commands in your terminal:

[[See Video to Reveal this Text or Code Snippet]]

This will tell you if your python command is pointing to Python 2 or Python 3.

The Solution

To resolve the issue and ensure you’re consistently using Python 3, follow these steps:

Use Python 3 Explicitly:
Instead of running your script using python, use:

[[See Video to Reveal this Text or Code Snippet]]

Check Python Installation:
Ensure that the psutil module is installed for Python 3:

[[See Video to Reveal this Text or Code Snippet]]

Modify Your Shell Script as Needed:
If your shebang is correctly set to # !/usr/bin/env python3, running it after setting executable permission will work because it directly uses Python 3.

Preferred Execution Method:
Use the executable method if you prefer to avoid typing python3 each time. Just ensure the shebang is correctly pointing to Python 3.

Conclusion

By understanding the difference between how your script is executed and the implications of using different Python versions, you can avoid the No module named psutil error in the future. Always ensure you’re running your scripts with the correct interpreter to utilize the modules you’ve installed.

If you have any further questions or need additional clarification, feel free to reach out!