pnmcat --version (return code: 0)
pnmcat: Using libpbm from Netpbm Version: Netpbm 10.0
pnmcat: BSD defined
pnmcat: RGB_ENV='RGBDEF'
pnmcat: RGBENV= 'RGBDEF' (env vbl is unset)
pnmcat -h (return code: 1)
usage: pnmcat [-white|-black] -leftright|-lr [-jtop|-jbottom] pnmfile ...
[-white|-black] -topbottom|-tb [-jleft|-jright] pnmfile ...