Line Printer Daemon protocol
Encyclopedia
The Line Printer Daemon protocol/Line Printer Remote protocol (or LPD, LPR) is a network protocol for submitting print jobs to a remote printer. The original implementation of LPD was in the Berkeley printing system
in the BSD UNIX operating system; the LPRng
project also supports that protocol. The Common Unix Printing System
(or CUPS), which is more common on modern Linux
distributions, supports LPD as well as the Internet Printing Protocol (IPP)
. Commercial solutions are available that also leverage Berkeley printing protocol components, where more robust functionality and performance is necessary than is available from LPR/LPD (or CUPS) alone (such as might be required in large corporate environments). The LPD Protocol Specification is documented in RFC 1179.
character.
An LPD printer is identified by the IP address of the server machine and the queue name on that machine. Many different queue names may exist in one LPD server, with each queue having unique settings. Note that the LPD queue name is case sensitive. Some modern implementations of LPD on network printers might ignore the case or queue name altogether and send all jobs to the same printer. Others have the option to automatically create a new queue when a print job with a new queue name is received. This helps to simplify the setup of the LPD server. Some companies (e.g. D-Link in model DP-301P+) have a tradition of calling the queue name “lpt1” or “LPT1”.
A printer that supports LPD/LPR is sometimes referred to as a "TCP/IP printer" (TCP/IP
is used to establish connections between printers and clients on a network), although that term would be equally applicable to a printer that supports the Internet Printing Protocol
.
Berkeley printing system
The Berkeley printing system is one of several standard architectures for printing on the Unix platform. It originated in 4.2BSD, and is used in BSD derivatives such as FreeBSD, NetBSD, OpenBSD, and DragonFly BSD...
in the BSD UNIX operating system; the LPRng
LPRng
LPRng is a printing system compatible with the Berkeley printing system. It provides printer spooling and network print server functionality using the Line Printer Daemon protocol....
project also supports that protocol. The Common Unix Printing System
Common Unix Printing System
CUPS is a modular printing system for Unix-like computer operating systems which allows a computer to act as a print server...
(or CUPS), which is more common on modern Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
distributions, supports LPD as well as the Internet Printing Protocol (IPP)
Internet Printing Protocol
In computing, the Internet Printing Protocol provides a standard network protocol for remote printing as well as for managing print jobs, media size, resolution, and so forth....
. Commercial solutions are available that also leverage Berkeley printing protocol components, where more robust functionality and performance is necessary than is available from LPR/LPD (or CUPS) alone (such as might be required in large corporate environments). The LPD Protocol Specification is documented in RFC 1179.
Usage
A server for the LPD protocol listens for requests on TCP port 515. A request begins with a byte containing the request code, followed by the arguments to the request, and is terminated by an ASCII LFNewline
In computing, a newline, also known as a line break or end-of-line marker, is a special character or sequence of characters signifying the end of a line of text. The name comes from the fact that the next character after the newline will appear on a new line—that is, on the next line below the...
character.
An LPD printer is identified by the IP address of the server machine and the queue name on that machine. Many different queue names may exist in one LPD server, with each queue having unique settings. Note that the LPD queue name is case sensitive. Some modern implementations of LPD on network printers might ignore the case or queue name altogether and send all jobs to the same printer. Others have the option to automatically create a new queue when a print job with a new queue name is received. This helps to simplify the setup of the LPD server. Some companies (e.g. D-Link in model DP-301P+) have a tradition of calling the queue name “lpt1” or “LPT1”.
A printer that supports LPD/LPR is sometimes referred to as a "TCP/IP printer" (TCP/IP
Internet protocol suite
The Internet protocol suite is the set of communications protocols used for the Internet and other similar networks. It is commonly known as TCP/IP from its most important protocols: Transmission Control Protocol and Internet Protocol , which were the first networking protocols defined in this...
is used to establish connections between printers and clients on a network), although that term would be equally applicable to a printer that supports the Internet Printing Protocol
Internet Printing Protocol
In computing, the Internet Printing Protocol provides a standard network protocol for remote printing as well as for managing print jobs, media size, resolution, and so forth....
.
See also
- Lp (Unix)Lp (Unix)The lp command is used on many Unix-like systems to assign jobs to printer queues. The name derives from "lineprinter", though it has become the commonly used command for any sort of printer...
- LPRngLPRngLPRng is a printing system compatible with the Berkeley printing system. It provides printer spooling and network print server functionality using the Line Printer Daemon protocol....
- Legacy printing
- Common Unix Printing System (CUPS)Common Unix Printing SystemCUPS is a modular printing system for Unix-like computer operating systems which allows a computer to act as a print server...
- RLPR
- System V printing systemSystem V printing systemThe UNIX System V printing system is one of several standard architectures for printing on the UNIX platform, and is typical of commercial System V-based operating systems such as Solaris and SCO OpenServer...
- SpoolingSpoolingIn computer science, spool refers to the process of placing data in a temporary working area for another program to process. The most common use is in writing files on a magnetic tape or disk and entering them in the work queue for another process. Spooling is useful because devices access data at...
- Print serverPrint serverA print server, or printer server, is a device that connects printers to client computers over a network. It can accept print jobs from the computers and send the jobs to the appropriate printers....
- Application layerApplication layerThe Internet protocol suite and the Open Systems Interconnection model of computer networking each specify a group of protocols and methods identified by the name application layer....
- FoomaticFoomaticFoomatic is a configurable printing filter. It uses PPD files as configuration to generate appropriate output for a given printer. It is intended to be used with the Common Unix Printing System . It uses ghostscript in the background, using options according to the PPD file of the printer...