Constructing a GPT disk image

[Brook Milligan <brook%nmsu.edu@localhost>]

I would like to construct a GPT disk image file, which I will later dd onto a real disk.  I am not sure how to do this, and so would appreciate any guidance.  Here is what I have found; please correct me if any of the following is incorrect.

- It seems that gpt will nicely label a file as if it were a disk and will add partitions as normal.

- I am not sure how to access those partitions, as dkctl complains if given a file as the first argument.

- vnconfig seems to want a file that corresponds to a single partition, not a partitioned disk.

This suggests one potential strategy:

- create a file for each partition

- mount it with vnconfig and populate the filesystem

- create a file for the disk image

- label the disk image with gpt

- dd each partition into the disk image with an appropriate seek= option to place it at the location of the partition

Is this a correct procedure?  Is it the best option?  What would be needed to recognize wedges in a GPT disk image so this could be simplified (i.e., create the GPT file image and mount the wedges directly)?

Any guidance is greatly appreciated.

Thanks a lot.

Cheers,
Brook