Xvfb -pixdepths 3 27 -fbdir /var/tmp
The server will listen for connections as server number 0, will
have the default screen configuration (one screen,
1280x1024x8), will also support pixmap depths of 3 and 27, and
will use memory mapped files in /var/tmp for the framebuffer.
xwud -in /var/tmp/Xvfb_screen0
Displays screen 0 of the server started by the preceding example.
You may need to install the xorg-x11-apps RPM package.