How did you uninstall it? The title bars in the screenshots show that the current command is still zsh, or maybe /bin/zsh.
If you changed this setting in Terminal's preferences, change it back to the default login shell:
If you changed the default login shell, you can change it back to /bin/bash with chsh -s /bin/bash.
That guide is very polished and super close to getting you an install, but I fear it isn't sufficient to get rails running.
The two things I've been able to reproduce is the rbenv isn't calling the proper version of gem to get rails installed and even after you rehash things, rails is still being called from /usr/bin and not where homebrew and rbenv are ...
By default /usr/local/lib is owned by root:wheel.
To install or uninstall gems you have to prepend sudo ....
There is no need to set up a new user, in particular because a new user won't change the permissions of the mentioned folder!
If you want to install gems with your current user without prepending sudo, change the permissions of the path /usr/local/...
You could try a tool that creates a virtual environment. That would allow you to download just the tools you need - correct versions, etc, and it's self-contained. That way you don't need to worry about the system's versions of your dependencies, nor the other users on your system. Apparently RVM is the Ruby version of what I had in mind.
You need to update Ruby.
Install home-brew (It will allow you to install software package from source): ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
brew install rbenv ruby-build
echo 'if which rbenv > /dev/null; then eval "$(rbenv init -)"; fi' >> ~/.bash_profile
First, check if you have Xcode installed
Second, if you already have Xcode in your Mac, use this command:
CC=gcc rvm install-version
CC=gcc rvm install-1.9.3
Reason for this error in Mac OS is that your Ruby is not able to get the C header files
Hope, this works on all the Macbook's.
Its working on El Capitan, ruby 1.9.3, rails 3.2, mysql 5.7