How Can I Safely Run External Commands in Python?

Running External Commands in Python

When working with Python, there may be instances where you need to execute an external program or call a system command as if you were typing it directly in a shell or command prompt. To achieve this, Python provides several methods, including subprocess and os.system.

Using subprocess.run

The recommended and preferred method is to use subprocess.run. It is versatile, safe, and offers more control compared to other options. Here's an example:

import subprocess

subprocess.run(["ls", "-l"])

Alternative Method: os.system

Another common approach is to use os.system. However, it is generally unsafe and discouraged as it lacks proper handling of spaces and special characters. Moreover, subprocess.run is more flexible and provides additional capabilities.

Using subprocess.call (Python 3.4 and Earlier)

Prior to Python 3.4, subprocess.call should be used instead of subprocess.run:

subprocess.call(["ls", "-l"])

Safety Considerations

It is essential to use caution when calling external commands within Python. Avoid using os.system if any part of the command comes from external sources or contains potentially malicious characters. Always prefer subprocess.run or subprocess.call, as they provide more control and security features.

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