We really need to know what you're trying to do with gpart.

For example, since you use gpart in order to check a partition table (and re-write it),

gpart /dev/hda

would seem a better choice.

http://www.stud.uni-hannover.de/user/76201/gpart/

has the author's description, but, essentially, you run gpart /dev/hda to check the partitions. If the check is consistent, use gpart gpart -W /dev/hda /dev/hda