How to find all the available tools in mac terminal? I am trying to setup a bunch of development projects in my Mac. I have to run various tools like python, ruby, scala, groovy etc. 
To see if a tool is available I use options like 

ruby --version. 


Instead I would like to see all the list of tools available in Mac terminal via a single command. What is the command/options for it?
The easiest is simply to open the Terminal and then press the TAB key twice. You'll be asked if you want to see all possibilities - reply "y" and you'll get the full list.