nis_addmember: Who checks for duplicate group members ? nisgrpadm or
               nis_addmember ?
nispasswd: Implement the missing flags, fix returncodes,
	   IMPORTANT: Use the expire, warn, ... flags
nisgrpadm: returncode if -t and -s parameter, fix -s parameter,
	   test, if principal is fully qualified

nis_cache2mgr: If we reload the COLD_START file, invalidate all cache entries

nischattrs: -f flag is missing

Missing programs:
      /usr/bin/nispasswd (shadow functions missing) 
      /usr/sbin/nisping 
