If any of the files localhosts, localnetworks, or localgateways are present in the current directory, the file's contents is prepended to the output file. Of these, only the gateways file is interpreted. This allows sites to maintain local aliases and entries which are not normally present in the master database. Only one gateway to each network will be placed in the gateways file; a gateway listed in the localgateways file will override any in the input file.
If the gateways file is to be used, a list of networks to which the host is directly connected is specified with the -c flag. The networks, separated by commas, may be given by name or in Internet-standard dot notation, for example, -c arpanet,128.32,local-ether-net. htable only includes gateways which are directly connected to one of the networks specified, or which can be reached from another gateway on a connected net.
If the -l option is given with a list of networks (in the same format as for -c), these networks will be treated as ``local'', and information about hosts on local networks is taken only from the localhosts file. Entries for local hosts from the main database will be omitted. This allows the localhosts file to completely override any entries in the input file.
htable is best used in conjunction with the
program which retrieves the NIC database from a