To do that, you need to edit the .bashrc file located in your home directory:
In order to create an alias for this command:
sudo apt-add-repository (the command used to add a ppa to your software sources), append the following line to the end of the .bashrc file:
alias add-ppa='sudo apt-add-repository'
Save the file and exit gedit. Next time when you want to add a ppa, just type:
PPA-ADDRESS is the ppa link. It begins with the prefix
ppa:. For example, you can use these commands to install Gimp:
sudo apt-get update
sudo apt-get install gimp
The general syntax for creating an alias is:
alias NewCommand='OldCommand' where NewCommand is an alias of your choice and OldCommand is the long command that you want to replace.