With OS X 10.8 Mountain Lion came some new Unix commands that are very handy. Among them is pgrep and pkill, which rolls grep into the ps command so you no longer have to pipe ps to grep in order to find a running process. pkill does the same thing, but kills each process that you’ve grepped for.
Also included in Mountain Lion are tools for enabling FileVault 2 from CLI, setting up file shares and a command that allows you to prevent system sleep until after the script completes (among other uses). This can come in handy because 10.8 has more agressive sleep than prior versions of OS X.Source: StackExchange Community Blog