Why does 'python3 --version' throw a 'NameError: name 'python3' is not defined'?

Python version command fails with "NameError"

When attempting to check the Python version by entering "python3 --version," a common error encountered is "NameError: name 'python3' is not defined." This issue stems from the misconception that Python syntax should be used in this command.

Python3 is not a command within the Python interpreter; rather, it is the Python binary itself. To display the Python version, open a command console (such as terminals in Linux or Mac, or Command Prompt in Windows). Avoid typing these commands at the Python prompt (denoted by ">>>" or "In [number]:").

Many other commands are also commonly mistaken for Python syntax and should be executed in the command prompt. Notable examples include:

• Python versions (e.g., python, python2.7, python3.5)
• Package managers (pip or pip3)
• Environment creation tools (virtualenv)
• Interactive Python shell (ipython)
• Installation tools (easy_install)
• Django management tool (django-admin)
• Conda environment manager (conda)
• Web frameworks (flask)
• Scraping frameworks (scrapy)
• Setup scripts (setup.py -- executed as "python setup.py [...])
• sudo prefixes for elevated privileges

If arguments are appended to these commands, a SyntaxError will be thrown. However, the underlying issue remains the same: these commands are meant to be executed outside of the Python interpreter.

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