Tip 17: Aliases
From Vlsiwiki
Aliases are effectively user-created command-line shortcuts. In Ubuntu, several aliases are already created to make life on the command line a little more attractive. To see what's already there, simply type:
$alias
To add more aliases, we can type something like
alias l="ls -al"
By default, Ubuntu also reads in a file in your home directory called .bash_aliases Simply add the line as above to that file and it will create the alias every time you start a new terminal window.