This can easily be solved by looking into the [Arch Wiki][1]:

> It is useful to have the auto-complete feature (pressing Tab key twice on the keyboard) after you type some command like sudo.

>To do this add a line in this format to your ~/.bashrc file:

>> complete -cf your_command

> For example, to enable auto-complete after sudo and man:

>> complete -cf sudo
>> complete -cf man



  [1]: https://wiki.archlinux.org/index.php/Bash#Auto-completion