Is Home brew a single use

I have just installed python 3.8.5 using Home-brew, but which python still says Python 2.7 installed. I had also installed , pyenv and home-brew. I closed the terminal and open a new one None of them are available in my zsh shell ‘command not found: brew’ Could someone update the installation instructions or does one have install them each time you open a new terminal.

Is /usr/local/bin in your path (echo $PATH)? Installation of brew should have warned you if it wasn’t. You do not need to install brew each time you open a new terminal.

Since the executable python is provided by apple, Brew is not replacing it. You need to call python3

It tells this when you did brew install python

At the end of the Homebrew install process, the installer would’ve said something like the following:

Next steps:
...
- Add Homebrew to your PATH in ~/.zprofile:
    echo 'eval $(/usr/local/bin/brew shellenv)' >> ~/.zprofile

I’m guessing you didn’t do that step?