papowell@attila.cs.umn.edu (06/16/88)
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PLP - The Public Line Printer Spooler
A Portable UNIX Line Printer Spooler
Release 2.0, 1 June 1988
Patrick Powell
Dept. of Computer Science
University of Minnesota, Minneapolis, Minnesota
PLP is a public domain version of the Berkeley LPD software.
The functional resemblance between PLP and the Berkeley Line
Printer Spooler (LPD) is intentional; the source code was written
without reference to the original Berkeley LPD software, except
for some very small sections concerned with networking and the
large characters used for banner printing. The PLP software has
the following features:
1).The PLP software is intended to be used in a Networked File
System (NFS) environment, in which there is a common set of
spool queues, as well as in a loosely coupled environment in
which each host transfers print jobs to a host which has the
printer.
2).Access and permission to use PLP functions is controlled by
entries in a printer permissions file
(/usr/spool/lpd/printer_perms.<hostname>) which can restrict
use by user name, host, spooler, page useage, and a host of
other factors. The printcap file
(/usr/spool/lpd/printcap.<hostname>) is used to specify the
printer queues and their operation.
3).Jobs can now be prioritized. The maximum priority a user can
specify is set in the printer permissions file.
4).In addition to the general printer permissions file, each
spool queue can have its own addition printer permissions
file.
5).Line printer control functions can be exercised from a remote
host. Hosts and users with remote control permission are
specified by entries in the printer permissions file.
6).Unspooling of jobs can be performed by a printcap specified
program, rather than by the PLP unspooler. This allows PLP to
be used as a spooler and to have spool queues used for various
purposes.
7).Extremely verbose and chatty error messages have been added.
These greatly ease debugging and installation. In addition,
the checkpc utility can be used to set file permissions and
other items for use by the PLP software.
8).The code is quite portable, with as few system dependencies in
it as possible. It has run on a VAX 4.2, 4.3, and ULTRIX, SUN
3.0, and DG-UX.
____________
* UNIX is a trademark of ATT Bell Laboratories.
Prof. Patrick Powell, Dept. Computer Science, 136 Lind Hall, 207 Church St. SE,
University of Minnesota, Minneapolis, MN 55455 (612)625-3543/625-4002