Discus is a program to display hard drive space usage, much like the standard
UNIX command df.

Discus aims to make df(1) prettier. Features include color, bar graphs, and
smart formatting of numbers (automatically choosing the most suitable size
from kilobytes, megabytes, gigabytes, or terabytes). Or choose your own size,
along with specifying the number of decimal places you'd like to see.

To configure Discus on a system-wide basis, edit the /usr/local/etc/discusrc
file. But you should probably change things just for yourself, by copying
/usr/local/etc/discusrc to ~/.discusrc and editing that.