It's very powerful. There's more than just the !! for history, also. Check out http://www.catonmat.net/blog/the-definitive-guide-to-bash-command-line-history/ h

It's very powerful. There's more than just the !! for history, also. Check out http://www.catonmat.net/blog/the-definitive-guide-to-bash-command-line-history/ http://www.catonmat.net/blog/the-definitive-guide-to-bash-co... .