We already check for (and reject entries with) '+' or '-' as the first
character of the key side of the key/data pair; we should check the data
side too. (Letting spurious +/- entries into the NIS maps is bad karma.)
This program is used for both generating and dumping NIS maps. It's very
similar to the 'makedbm' command in SunOS. This program was ported from
the yps-0.21 package. It's close to the original except for the GDBM to
DB conversions. This was simple compared to the other YP components.