[lastrachris]

Whenever I try to log in as a super user, I usually execute the command: su <enter> [my password] <enter>
It is always telling me that authentication failed. However, I know the password is correct, and no other programs were running in super user, not even updates. In addition I have a .sh I usually can execute to run a java file in the terminal. When I try to run the file, after applying proper permissions, nothing happens. What's wrong?

[arochester]

According to Wikipedia Peppermint OS is a derivative of Ubuntu. Ubuntu does not use su - it uses sudo instead.

sudo for non-graphical apps e.g. Terminal apps
gksudo for graphical e.g. GUI apps

Have you tried that?