How do I configure my Terminal app with bash and iTerm2 with zshell and oh my zsh?
If your default system shell is bash, your Terminal should start with it. You can check it on General tab under Terminal Preferences. Should look like the following:
If bash isn't your default shell, you can change it by typing:
chsh -s /bin/bash
To configure iTerm2 with zsh you have to open Preferences and change the command on General tab on your default profile. You have to enter /bin/zsh or whatever shell you want.
To install oh-my-zsh type the following:
sh -c "$(curl -fsSL https://raw.github.com/robbyrussell/oh-my-zsh/master/tools/install.sh)"