Print Release System provides Web-based management of System V printing. It sits between Samba and the System V printing system. It ought to be relatively easy to make it work with other printing systems. After the job is printed, the user needs to consult a Web page that shows their queued jobs, which can be selected and released for printing (or canceled). A record is maintained for each job and, once the user reaches a quota, they can't release any further jobs to the printer.
