You know a linux command will perform a desired function for you, but you cannot remember the full name of the command. you do remember it will flush a variable from your system. which command typed at a command prompt displays a list of commands that would likely contain the command you desire?

What need most led to the creation of the advanced research projects agency network? darpa wanted scientists to be able to collaborate and share research easily. darpa wanted american and russian politicians to be able to communicate. darpa wanted astronauts to be able to contact nasa and the white house. darpa wanted factory owners to be able to coordinate supply chains.