Provided by: cups_2.1.3-4_amd64 bug

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 cupsParseOptions() 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 "landscape"
       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 cupsMarkOptions() 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 typically used to update
            default option keywords such as DefaultPageSize 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 leading 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 Processors (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,  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.

NOTES

       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
       OS X) 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 appropriate filters to do the conversions you need.

SEE ALSO

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

COPYRIGHT

       Copyright © 2007-2015 by Apple Inc.