# install Homebrew
# /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

# install Bash via Homebrew
brew update && brew install bash

# Add the new shell to the list of allowed (white-listed) shells
# sudo bash -c 'echo /usr/local/bin/bash >> /etc/shells'
echo "$(brew --prefix)/bin/bash" >> /etc/shells

# Change to the new shell
chsh -s $(brew --prefix)/bin/bash 

• sudo -i let’s you switch to root user
• brew --prefix gives you the location of Homebrew install directory (/usr/local by default)
• cat /etc/shells gives you the list of allowed shells