In the previous section, two pieces of information included in the _pmtab file were described: the port monitor's version number and the port monitor part of the service entries in the port monitor's _pmtab file. When you add a new port monitor, the version number must be known so that the _pmtab file can be correctly initialized. When you add a new service, the port monitor part of the _pmtab entry must be formatted correctly.
Each port monitor must have an administrative command to perform these two tasks. The person who defines the port monitor must also define such an administrative command and its input options. When the command is invoked with these options, the information required for the port monitor part of the service entry must be correctly formatted for inclusion in the port monitor's _pmtab file and must be written to the standard output. To request the version number, the command must be invoked with a -V option. When it is invoked in this way, the port monitor's current version number must be written to the standard output.