Typical usage looks like this:
dmgbuild -s settings.py "Volume Name" output.dmg
settings.py file specifies the attributes that
control the appearance of the disk image. The other arguments give
the volume name and the name of the output file respectively.
dmgbuild also accepts arguments of the form
these can be used from within the settings file, for instance so that
you can write a single settings file for multiple disk images, or so
that you can easily alter settings at build time.