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man pages section 7: Standards, Environments, Macros, Character Sets, and Miscellany

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Updated: Wednesday, February 9, 2022
 
 

filter (7)

Name

filter - cups file conversion filter interface

Synopsis

filter job user title num-copies options [ filename ]

#include <cups/cups.h>

ssize_t cupsBackChannelRead(char *buffer, size_t bytes,
double timeout);

cups_sc_status_t cupsSideChannelDoRequest(cups_sc_command_t command,
char *data, int *datalen,
double timeout);

#include <cups/ppd.h>

const char *cupsGetOption(const char *name, int num_options,
cups_option_t *options);

int cupsMarkOptions(ppd_file_t *ppd, int num_options,
cups_option_t *options);

int cupsParseOptions(const char *arg, int num_options,
cups_option_t **options);

ppd_choice_t *ppdFindMarkedChoice(ppd_file_t *ppd, const char *keyword);

void ppdMarkDefaults(ppd_file_t *ppd);

ppd_file_t *ppdOpenFile(const char *filename);

Description

filter(7)                         Apple Inc.                         filter(7)



NAME
       filter - cups file conversion filter interface

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

       #include <cups/cups.h>

       ssize_t cupsBackChannelRead(char *buffer, size_t bytes,
                                   double timeout);

       cups_sc_status_t cupsSideChannelDoRequest(cups_sc_command_t command,
                                                 char *data, int *datalen,
                                                 double timeout);

       #include <cups/ppd.h>

       const char *cupsGetOption(const char *name, int num_options,
                        cups_option_t *options);

       int cupsMarkOptions(ppd_file_t *ppd, int num_options,
                           cups_option_t *options);

       int cupsParseOptions(const char *arg, int num_options,
                            cups_option_t **options);

       ppd_choice_t *ppdFindMarkedChoice(ppd_file_t *ppd, const char *keyword);

       void ppdMarkDefaults(ppd_file_t *ppd);

       ppd_file_t *ppdOpenFile(const char *filename);

DESCRIPTION
       The CUPS filter interface provides a standard method for adding support
       for new document types or printers 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.  Filters MUST NOT attempt to communicate directly with
       the printer, other processes, or other services.

       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 are passed in argv[5] and are encoded  from  the  corresponding
       IPP  attributes  used  when the job was submitted. Use the cupsParseOp-
       tions() function to load the options into a cups_option_t array and the
       cupsGetOption()  function to get the value of a specific attribute.  Be
       careful to look for common aliases of IPP  attributes  such  as  "land-
       scape" for the IPP "orientation-requested" attribute.

       Options passed on the command-line typically do not include the default
       choices the printer's PPD file. Use  the  ppdMarkDefaults()  and  cups-
       MarkOptions() functions in the CUPS library to apply the options to the
       PPD defaults and map  any  IPP  attributes  to  the  corresponding  PPD
       options.  Use ppdFindMarkedChoice() to get the user-selected choice for
       a PPD option. For example, a filter might use  the  following  code  to
       determine the current value of the Duplex PPD option:

           ppd_file_t *ppd = ppdOpenFile(getenv("PPD"));
           cups_option_t *options = NULL;
           int num_options = cupsParseOptions(argv[5], 0, &options);

           ppdMarkDefaults(ppd);
           cupsMarkOptions(ppd, num_options, options);

           ppd_choice_t *choice = ppdFindMarkedChoice(ppd, "Duplex");

       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  the  standard  error  are  generally  stored  in  the
       printer's  "printer-state-message"  attribute  and the current ErrorLog
       file.  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  or  printer attribute(s). The following job
            attributes can be set: "job-media-progress". The following printer
            attributes  can  be  set:  "auth-info-required",  "marker-colors",
            "marker-high-levels",    "marker-levels",     "marker-low-levels",
            "marker-message", "marker-names", "marker-types", "printer-alert",
            and "printer-alert-description".

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

       DEBUG: message
            Adds  the  specified  message  to  the  current ErrorLog using the
            "debug" log  level.   DEBUG  messages  are  never  stored  in  the
            "printer-state-message" attribute.

       DEBUG2: message
            Adds  the  specified  message  to  the  current ErrorLog using the
            "debug2" log level.  DEBUG2  messages  are  never  stored  in  the
            "printer-state-message" attribute.

       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  for  the
            current  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 media type associated with the submitted  job  file,  for
            example "application/postscript".

       CUPS_CACHEDIR
            The  directory  where semi-persistent cache files can be found and
            stored.

       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_MAX_MESSAGE
            The  maximum size of a message sent to stderr, including any lead-
            ing prefix and the trailing newline.

       CUPS_SERVERROOT
            The root directory of the server.

       FINAL_CONTENT_TYPE
            The MIME media type associated with the output  destined  for  the
            printer, for example "application/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/major.minor).

       TZ   The timezone of the server.

       USER The  user  executing the filter, typically "lp" or "root"; consult
            the cups-files.conf file for the current setting.

CONFORMING TO
       While the filter  interface  is  compatible  with  System  V  interface
       scripts, CUPS does not support System V interface scripts.


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+------------------+
       |ATTRIBUTE TYPE | ATTRIBUTE VALUE  |
       +---------------+------------------+
       |Availability   | print/cups       |
       +---------------+------------------+
       |Stability      | Volatile         |
       +---------------+------------------+

NOTES
       CUPS  printer drivers and backends are deprecated and will no longer be
       supported in a future feature release of CUPS.  Printers  that  do  not
       support   IPP   can   be   supported   using   applications   such   as
       ippeveprinter(1).

       CUPS filters are not meant to be run directly by the user.  Aside  from
       the  legacy  System  V  interface issues (argv[0] is the printer name),
       CUPS filters  also  expect  specific  environment  variables  and  file
       descriptors,  and  typically  run in a user session that (on macOS) has
       additional restrictions that affect how it  runs.   Unless  you  are  a
       developer  and  know  what  you  are  doing,  please do not run filters
       directly.  Instead, use the cupsfilter(8) program to use the  appropri-
       ate filters to do the conversions you need.

       Source  code  for open source software components in Oracle Solaris can
       be found at https://www.oracle.com/downloads/opensource/solaris-source-
       code-downloads.html.

       This     software     was    built    from    source    available    at
       https://github.com/oracle/solaris-userland.   The  original   community
       source    was    downloaded   from    https://github.com/apple/cups/ar-
       chive/v2.3.3.zip.

       Further information about this software can be found on the open source
       community website at http://www.cups.org/.

SEE ALSO
       backend(7), cups(1), cups-files.conf(5), cupsd(8), cupsfilter(8),
       CUPS Online Help (http://localhost:631/help)

COPYRIGHT
       Copyright (C) 2007-2019 by Apple Inc.




26 April 2019                        CUPS                            filter(7)