How to enable TAB auto completion in Mac OS X Terminal? It’s easy.

Firstly, edit the .inputrc file in your Home directory. Execute the following commands:

cd ~
vi .inputrc

Then, add the following content:

set completion-ignore-case on
set show-all-if-ambiguous on
TAB: menu-complete

Relaunch Terminal. Auto complete should be switched on now. Cycle through all the auto complete options by pressing TAB.