Troubleshooting "NameError: Name 'python3' is Not Defined" in Python
When attempting to check the Python version using the command "python3 --version," you may encounter the error "NameError: name 'python3' is not defined." This error arises due to a misunderstanding of the distinction between the Python binary and the Python prompt.
Python3 is not a Python syntax but rather the Python binary, the executable that allows you to access the interactive interpreter. You are currently mistakenly entering the command at the Python prompt (identified by the ">>>" or "In [number]:" symbol), which accepts only Python code.
To correctly check the Python version, open a command line (Windows) or terminal (Linux, Mac). This is a separate interface from the Python interpreter. At the command line, type "python3 --version" (or simply "python3" on some systems), and the command will print the Python version installed on your system.
Similarly, when installing Python modules with pip, you should run the pip command on the system command line, not within the Python interpreter. To do so, type "pip install --user" followed by the package name (e.g., "pip install --user package_name").
Remember that command-line programs often have names that resemble Python syntax, such as "python," "pip," "virtualenv," and "ipython." However, these programs are not actually Python commands but are invoked from the command line. Avoid the common mistake of mistaking these programs for Python syntax.
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