redhat man page for filter

filter(1)						      Easy Software Products							 filter(1)

NAME
       filter - cups file conversion filter interfaces

SYNOPSIS
       filter job user title num-copies options [ filename ]

DESCRIPTION
       The  CUPS filter interface provides a standard method for adding support for new document types to CUPS. Each filter is capable of convert-
       ing from one or more input formats to another format that can either be printed directly or piped into another filter to get it to a print-
       able format.

       Filters	must  be capable of reading from a filename on the command-line or from the standard input, copying the standard input to a tempo-
       rary file as required by the file format. All output must be sent to the standard output.

       The command name (argv[0]) is set to the name of the destination printer.

ENVIRONMENT VARIABLES
       The following environment variables are defined by the CUPS server when executing each filter:

       CHARSET
	    The default text character set (typically us-ascii or iso-8859-1).

       CLASS
	    When a job is submitted to a printer class, contains the name of the destination printer class. Otherwise  this  environment  variable
	    will not be set.

       CONTENT_TYPE
	    The MIME type associated with the file (e.g. application/postscript).

       CUPS_DATADIR
	    The directory where data files can be found.

       CUPS_SERVERROOT
	    The root directory of the server.

       DEVICE_URI
	    The device-uri associated with the printer.

       LANG
	    The default language locale (typically C or en).

       PATH
	    The standard execution path for external programs that may be run by the filter.

       PPD
	    The full pathname of the PostScript Printer Description (PPD) file for this printer.

       PRINTER
	    The name of the printer; this is provided for shell scripts which may not be able to get the passed argv[0] string.

       RIP_CACHE
	    The recommended amount of memory to use for Raster Image Processors (RIPs).

       SOFTWARE
	    The name and version number of the server (typically CUPS/1.1).

       TZ
	    The timezone of the server.

       USER
	    The user executing the filter (typically lp).

COMPATIBILITY
       While  the filter interface is compatible with System V interface scripts, it will only work with the System V interface script as the only
       filter.	Typically the interface script will be provided via the lpadmin(8) command using the -i option.

SEE ALSO
       backend(1), cupsd(8),  CUPS  Interface  Design  Description,  CUPS  Software  Administrators  Manual,  CUPS  Software  Programmers  Manual,
       http://localhost:631/documentation.html

COPYRIGHT
       Copyright 1993-2002 by Easy Software Products, All Rights Reserved.

22 June 2000						    Common UNIX Printing System 						 filter(1)