If you executed a command and neglected to use sudo, you can execute
sudo !! to re-execute the previous command with sudo prepended.
Source: unknown, ubuntu-server-tips package
You can do this trick with any command. Like this:
$ google.com google.com: command not found $ curl !! curl google.com # html output
And similarly, you can repeat the last element of the command with
$_ like this:
~ $ mkdir test && cd $_ ~/test $