Aug 082012
Today I want to share with you some of my favorite features of bash, I called them hidden because I’ve discovered that a lot of people don’t know or don’t use them, but to be honest they are not so hidden after all, they are in the man page of bash, but how many of us have read it all ?
1) 
Thanks to xkcd.com for this explanation.
In short this is useful when you need root access for a command and you forget to use sudo.
The parameter “!!” is substituted with the last run command.
