LP Print Service (Reference)

This chapter provides background information on the LP print service.

• "The Structure of the LP Print Service"

• "LP Print Service Commands"

• "Functions of the LP Print Service"

• "How LP Administers Files and Schedules Local Print Requests"

• "Scheduling Network Print Requests"

• "Filtering Print Files"

• "What the Printer Interface Program Does"

• "How the lpsched Daemon Tracks the Status of Print Requests"

• "Cleaning Out Log Files"

Where to Find Printer Tasks

The LP Print Service

The LP print service is a set of software utilities that allows users to print files while they continue to work. Originally, the print service was called the LP spooler. (LP stood for line printer, but its meaning now includes many other types of printers, such as laser printers. Spool is an acronym for system peripheral operation off-line.)

The print service consists of the LP print service software, any print filters you might provide, and the hardware (the printer, system, and network connections).

The Structure of the LP Print Service

This section describes the directory structure, files, logs, and commands of the LP print service.

LP Print Service Directories

The files of the LP print service are distributed among seven directories, as shown in the following table.

Table 8-1 Directories for the LP Print Service

LP Print Service Configuration Files

The scheduler stores configuration information in LP configuration files located in the /etc/lp directory, as described in the following table.

Caution - The configuration files listed in this table are private interfaces, and are subject to change in future releases. You should not build software that relies on these files being in their current locations or that relies on the data being in the format currently used.

Table 8-2 Contents of the /etc/lp Directory

These configuration files serve a similar function to the /etc/printcap file on lpd-based print servers.

Note - You can check the contents of the configuration files, but you should not edit them directly. Instead, use the lpadmin command to make configuration changes. Your changes will be written to the configuration files in the /etc/lp directory. The lpsched daemon administers and updates the configuration files.

The /etc/lp/printers directory has a subdirectory for each local printer known to the system. The following example shows the /etc/lp/printers subdirectories of printers sparc1 and luna.

$ ls -l /etc/lp/printers
drwxrwxr-x 2 lp lp 512 Jan 23 23:53 luna
drwxrwxr-x 2 lp lp 512 Jan 11 17:50 sparc1

The following table describes the files within each of the printer-specific directories.

The configuration file for the printer luna, /etc/lp/printers/luna/configuration, would typically appear as follows:

Banner: on: Always
Content types: PS
Device: /dev/term/b
Interface: /usr/lib/lp/model/standard
Printer type: PS
Modules: default

The terminfo Database

The /usr/share/lib directory contains the terminfo database directory, which contains definitions for many types of terminals and printers. The LP print service uses information in the terminfo database to initialize a printer, to establish a selected page size, character pitch, line pitch, and character set, as well as to communicate the sequence of codes to a printer.

Each printer is identified in the terminfo database with a short name. For a description of the structure of the terminfo database, see "Printer Type". If necessary, you can add entries to the terminfo database, but it is a tedious and time-consuming process. For more information, see "Adding a terminfo Entry for an Unsupported Printer".

Daemons and LP Internal Files

The /usr/lib/lp directory contains daemons and files used by the LP print service, as described in the following table.

Table 8-3 Contents of the /usr/lib/lp Directory