Figuring out how to use gerbv was an utter pain. You type ‘gerbv’ at the prompt and the gui loads up but it refuses to accept the drd files etc via the ‘Project Box’… Guess (a) I should have slept and (b) RTFM!

GENERAL
When you start gerbv you can give the files to be loaded on the command
line, either as each file separated with a space or by using wildcards.

The user interface is graphical. Simply press left mouse button and the
image will pan as you move the mouse. To manipulate a layer, right-
click on one of the rightmost buttons. That will bring up a pop-up menu
where you can select what you want to do with that layer (load file,
change color, etc).

If you hold the mouse button over one the rightmost button a tooltips
will show you the name of the file loaded on that layer.

Default of concurrently loaded files are 20 layers. You can change this
during configure with:

./configure with-maxfiles=

My gerbv comand line was,

[15:46:10] kurosaki-ichigo:~/Documents/eagle/Projects/RC_Voltmeter michaeldesilva$ gerbv *.drd *.cmp *.sol *.stc *.sts *.plc *.pls