For practical use you want the xvfb-run wrapper script, and use a saner mode than the default 256-color one: xvfb-run --auto-servernum --server-args="-screen

For practical use you want the xvfb-run wrapper script, and use a saner mode than the default 256-color one: xvfb-run --auto-servernum --server-args="-screen 0, 1024x868x24" firefox