filter(7)			  Apple Inc.			     filter(7)



NAME
       filter - cups file conversion filter interface

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  converting
       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  printable
       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  temporary
       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 but is also available in the PRINTER environment variable.


OPTIONS
       Options passed on the command-line typically do not include the default
       choices the printer's PPD file. In addition, some options may be speci-
       fied  in	 multiple  ways	 -  "landscape" is a synonym for "orientation-
       requested=4",  "media"  is  a  synonym  for  "PageSize",	 "PageRegion",
       "InputSlot",  and "MediaType", and "sides" is a synonym for the various
       "Duplex" options. Non-raster filters must  support  both	 explicit  and
       implicit	 specification	of  PPD	 options - use the ppdMarkDefaults and
       cupsMarkOptions functions in the CUPS library to use the	 correct  map-
       ping, and ppdFindMarkedChoice to get the user-selected choice.

       Raster  filters	should	use option choices set through the raster page
       header, as those reflect the  options  in  effect  for  a  given	 page.
       Options	specified on the command-line determine the default values for
       the entire job, which can be overridden on a per-page basis.


LOG MESSAGES
       Messages sent to stderr are generally logged  to	 printer-state-message
       attribute  and  the current ErrorLog.  Each line begins with a standard
       prefix:


       ALERT: message
	    Sets the printer-state-message attribute and  adds	the  specified
	    message to the current ErrorLog using the "alert" log level.


       ATTR: attribute=value [attribute=value]
	    Sets  the  named  job attribute(s). Typically this will be used to
	    set the job-remote-id attribute.


       CRIT: message
	    Sets the printer-state-message attribute and  adds	the  specified
	    message to the current ErrorLog using the "critical" log level.


       DEBUG: message
	    Sets  the  printer-state-message  attribute and adds the specified
	    message to the current ErrorLog using the "debug" log level.


       DEBUG2: message
	    Sets the printer-state-message attribute and  adds	the  specified
	    message to the current ErrorLog using the "debug2" log level.


       EMERG: message
	    Sets  the  printer-state-message  attribute and adds the specified
	    message to the current ErrorLog using the "emergency" log level.


       ERROR: message
	    Sets the printer-state-message attribute and  adds	the  specified
	    message to the current ErrorLog using the "error" log level.


       INFO: message
	    Sets  the printer-state-message attribute. If the current LogLevel
	    is set to "debug2", also adds the specified message to the current
	    ErrorLog using the "info" log level.


       NOTICE: message
	    Sets  the  printer-state-message  attribute and adds the specified
	    message to the current ErrorLog using the "notice" log level.


       PAGE: page-number #-copies

       PAGE: total #-pages
	    Adds an entry to the current PageLog. The first form adds #-copies
	    to	the job-media-sheets-completed attribute. The second form sets
	    the job-media-sheets-completed attribute to #-pages.


       PPD: Keyword=Value ... KeywordN=Value
	    Sets the named keywords in the printer's PPD file. This  is	 typi-
	    cally  used to update default option keywords such as DefaultPage-
	    Size and the various installable options in the PPD file.


       STATE: printer-state-reason [printer-state-reason ...]

       STATE: + printer-state-reason [printer-state-reason ...]

       STATE: - printer-state-reason [printer-state-reason ...]
	    Sets, adds, or removes printer-state-reason keywords to  the  cur-
	    rent  queue.  Typically  this  is used to indicate media, ink, and
	    toner conditions on a printer.


       WARNING: message
	    Sets the printer-state-message attribute and  adds	the  specified
	    message to the current ErrorLog using the "warning" log level.


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


       CHARSET
	    The default text character set, typically utf-8.


       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/post-
	    script).


       CUPS_CACHEDIR
	    The directory for semi-persistent cache files can be found.


       CUPS_DATADIR
	    The directory where data files can be found.


       CUPS_FILETYPE
	    The	 type of file being printed: "job-sheet" for a banner page and
	    "document" for a regular print file.


       CUPS_SERVERROOT
	    The root directory of the server.


       DEVICE_URI
	    The device-uri associated with the printer.


       FINAL_CONTENT_TYPE
	    The	 MIME  type  associated	 with  the  printer  (e.g.    applica-
	    tion/vnd.cups-postscript).


       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.


       RIP_CACHE
	    The	 recommended  amount of memory to use for Raster Image Proces-
	    sors (RIPs).


       SOFTWARE
	    The name and version number of the server (typically CUPS/1.2).


       TZ
	    The timezone of the server.


       USER
	    The user executing the filter, typically "lp" or  "root";  consult
	    the cupsd.conf(5) file for the current setting.


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(7), cupsd(8),
       http://localhost:631/help

COPYRIGHT
       Copyright 2007-2009 by Apple Inc.



13 May 2009			     CUPS			     filter(7)