Install pg and mysql gems
This is not entirely realted to ruby but if you ever program with ruby you will find yourself using pg and mysql gems and the issue is how exactly do I install them. This mini-post (rather tumble) is just to make a note of this. Run the following in Teerminal.
PostgreSql
export PATH=/usr/local/pgsql/bin:${PATH} gem install pg
MySql
export PATH=/usr/local/mysql/bin:${PATH} gem install mysql
Also, please note that you should have postgres and mysql installed on your machine.