> sudo pip install https://github.com/wandernauta/yuml/zipball/master
> echo "[You]-(Draw Diagrams)" | ./yuml -t usecase -s scruffy -o diagram.png
curl -X POST -d "dsl_text=[Curl]->[Example]-.-[Nice{bg:wheat}]" https://yuml.me/diagram/scruffy/class/
This returns the filename with svg extension - e3c59524.svg
You can then download with whatever extension you like (svg, png, pdf, jpg, json).
curl https://yuml.me/e3c59524.png --output test.png
Hope this helps!
Tobin