Invocation
==========

The scripts can generally just be run. Options can be set on the
command line or by exporting variables to override those present in
lib/img-defaults. -h to get help.

The image building scripts expect to be able to invoke commands with
sudo, so if you want them to run non-interactively, you should either
run them as root, with sudo -E, or allow your build user to run any
sudo command without password.

Using the variable ``ELEMENTS_PATH`` will allow to specify multiple
elements locations.  It is a colon (:) separated path list, and it
will work in a first path/element found, first served approach. The
included elements tree is used when no path is supplied, and is added
to the end of the path if a path is supplied.

By default, the image building scripts will not overwrite existing
disk images, allowing you to compare the newly built image with the
existing one. To change that behaviour, set the variable
``OVERWRITE_OLD_IMAGE`` to any value that isn't ``0``. If this value is
zero then any existing image will be moved before the new image is
written to the destination.

Setting the variable ``DIB_SHOW_IMAGE_USAGE`` will print out a
summarised disk-usage report for the final image of files and
directories over 10MiB in size.  Setting ``DIB_SHOW_IMAGE_USAGE_FULL``
will show all files and directories.  These settings can be useful
additions to the logs in automated build situations where debugging
image-growth may be important.
