papowell@vlsi.cs.umn.edu (09/21/89)
The PLP software is available using anonymous FTP from vlsi.cs.umn.edu, (128.101.230.15), pub/PLP.<version>.tar.Z PLP (Public Line Printer) is a Berkeley LPD clone, with many interesting features such as: 1. Diagnostic messages. This is incredibly helpful when trying to find out why things are not working. 2. Engineered with NFS and other file systems in mind. For example- printcap: the software looks in three places for a printcap file /usr/spool/lpd/printcap.<hostname> /etc/printcap /usr/etc/printcap and uses the first one it finds. If you have hardware attached to your system, you tailor /usr/spool/lpd/printcap.<hostname> If you want to be Berkeley compatible, you can stick with /etc/printcap. However, if you mount /usr/etc from a remote host, then the remote host can provide you with the printcap information that you need. /usr/spool: you can have a single shared spool directory NSF mounted from all clients. This solves the problems of blowing away your spool directory on systems that have piddling little amounts of space dedicated to clients. 3. Multiple servers for a single queue- you can have multiple printers for a single queue. (The other one, single printer for multiple queues is not present, but may be added sometime). 4. Priorities. Absolute priorities + aging algorithm. 5. Permissions restrictions. You can indicate what hosts/user combinations can use a particular printer/spool queue. 6. Unspooling program. When LPD detects an entry in a queue, it can be told to invoke a program to handle the queue entries. This is handy when your queue involves horrible things like trying to send stuff to a remote site by ftp. This can be done on a per job or per queue basis. 7. You can remotely control queue facilities. This is a godsend in a distributed environment. 8. It has been running under just about all UNIX clones/versions around that support TCP/IP. This is done through a most obnoxious set of flags in the Makefile. Someday I will get around to adding Config to the distribution to simplify things. 9. There is even a way to build a test version of the software so that you can debug it without having to clobber the current LPD. Patrick Powell Prof. Patrick Powell, Dept. Computer Science, EECS 4-192, University of Minnesota, Minneapolis, MN 55455 (612)625-3543/625-4002