compare 2 stl files
$ diff piece-1.stl piece-3.stl
Binary files piece-1.stl and piece-3.stl differ
$ ./stl-cmp piece-1.stl piece-3.stl
all triangle from piece-1.stl are found in piece-3.stl
all triangle from piece-3.stl are found in piece-1.stl
STL are identicals