The addprinter command can be configured to be a shell script or program executed by Samba. It is triggered by running the APW from a client against the Samba print server. The APW asks the user to fill in several fields (such as printer name, driver to be used, comment, port monitor, and so on). These parameters are passed on to Samba by the APW. If the addprinter command is designed in a way that it can create a new printer (through writing correct printcap entries on legacy systems or by executing the lpadmin command on more modern systems) and create the associated share, then the APW will in effect really create a new printer on Samba and the UNIX print subsystem!