macOS BigSur 上 python 版本的问题

Question

I have a problem with the python version. I downloaded and installed the latest version of python directly from the site, 3.9.0, but when I check the version from the terminal using the python --version command, 2.7.16 is installed and installing the PIP package manager I get this in response:

DEPRECATION: Python 2.7 reached the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 is no longer maintained. pip 21.0 will drop support for Python 2.7 in January 2021. More details about Python 2 support in pip can be found at https://pip.pypa.io/en/latest/development/release-process/#python-2-support pip 21.0 will remove support for this functionality.
Defaulting to user installation because normal site-packages is not writeable
Collecting pip
Downloading pip-20.2.4-py2.py3-none-any.whl (1.5 MB)|████████████████████████████████| 1.5 MB 1.7 MB/s 
Installing collected packages: pip

WARNING: The scripts pip, pip2 and pip2.7 are installed in '/Users/user/Library/Python/2.7/bin' which is not on PATH.
Consider adding this directory to PATH or, if you prefer to suppress this warning, use --no-warn-script-location.
Successfully installed pip-20.2.4

Answer 1

[edit] (thanks to @JohnVargo)
Big Sur uses zsh by default, therefore you must amend the .zprofile i/o the .bash_profile . ...Unless you changed the default to use bash , then do as follows:
[/edit]

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If you want to use python to launch python3 from the command line, you can go to your home directory and edit your ~/.bash_profile by adding the following lines:

in terminal type $ which python this will return the path to the system python2 interpreter; let's call this path_to_p2

in terminal type $ which python3 this will return the path to the system python3 interpreter; let's call this path_to_p3

export PATH=path_to_p3:$PATH
alias python3=path_to_p3
alias python=path_to_p3

export PATH=path_to_p2:$PATH
alias python2=path_to_p2

save, relaunch terminal; You can now launch python3 with either python , or python3 , and python2 with python2

Answer 2

This is because macOS uses python 2 by default. So run your commands with python3 Then it'll only use python 3.