MacOS Catalina uses zsh by default, if you are using the same you want to add the line to ~/.zshrc
Discovered: Sep 29, 2020. rbenv in catalina: MacOS Catalina uses zsh by default, if you are using the same you want to add the line to ~/.zshrc “the line” is:
eval "$(rbenv init -)"
As of this writing, stable ruby is 2.7.1, here’s how to install ruby 2.7.1 using homebrew:
brew update
brew install ruby-build
brew install rbenv
rbenv install 2.7.1
rbenv global 2.7.1