I'm also running on Ubuntu, can I use the 'sort -u' options as well?
Yes, Ubuntu (and all other Linuxes and BSD's etc) implement all
standard (Unix) shell commands.
If you at some time enter some non-standard command that is currently
not installed, Ubuntu will
tell you that you can install the package that contains the command
directly frmo the command line
(using "sudo apt-get install <package>") and then immediately
retry the missing command. Very handy.