[thirdparty/cups.git] / doc / help / man-filter.html

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<h1 class="title">filter(7)</h1>
<h2 class="title"><a name="NAME">Name</a></h2>
filter - cups file conversion filter interface
<h2 class="title"><a name="SYNOPSIS">Synopsis</a></h2>
<b>filter</b>
<i>job</i>
<i>user</i>
<i>title</i>
<i>num-copies</i>
<i>options</i>
[
<i>filename</i>
]
<pre class="man">

<b>#include &lt;cups/cups.h></b>

<b>ssize_t cupsBackChannelRead</b>(<b>char *</b><i>buffer</i>, <b>size_t </b><i>bytes</i>,
                            <b>double </b><i>timeout</i>);

<b>cups_sc_status_t cupsSideChannelDoRequest</b>(<b>cups_sc_command_t </b><i>command</i>,
                                          <b>char *</b><i>data</i>, <b>int *</b><i>datalen</i>,
                                          <b>double </b><i>timeout</i>);

<b>#include &lt;cups/ppd.h></b>

<b>const char *cupsGetOption</b>(<b>const char *</b><i>name</i>, <b>int </b><i>num_options</i>,
                 <b>cups_option_t *</b><i>options</i>);

<b>int cupsMarkOptions</b>(<b>ppd_file_t *</b><i>ppd</i>, <b>int </b><i>num_options</i>,
                    <b>cups_option_t *</b><i>options</i>);

<b>int cupsParseOptions</b>(<b>const char *</b><i>arg</i>, <b>int </b><i>num_options</i>,
                     <b>cups_option_t **</b><i>options</i>);

<b>ppd_choice_t *ppdFindMarkedChoice</b>(<b>ppd_file_t *</b><i>ppd</i>, <b>const char *</b><i>keyword</i>);

<b>void ppdMarkDefaults</b>(<b>ppd_file_t *</b><i>ppd</i>);

<b>ppd_file_t *ppdOpenFile</b>(<b>const char *</b><i>filename</i>);
</pre>
<h2 class="title"><a name="DESCRIPTION">Description</a></h2>
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.
<p>Filters <b>MUST</b> 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 <b>MUST</b> be sent to the standard output.
Filters <b>MUST NOT</b> attempt to communicate directly with the printer, other processes, or other services.
<p>The command name (<i>argv[0]</i>) is set to the name of the destination printer but is also available in the <b>PRINTER</b><i> environment variable.
</i><h2 class="title"><a name="OPTIONS">Options</a></h2>
Options are passed in <i>argv[5]</i> and are encoded from the corresponding IPP attributes used when the job was submitted. Use the
<b>cupsParseOptions</b>()
function to load the options into a <b>cups_option_t</b> array and the
<b>cupsGetOption</b>()
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.
<p>Options passed on the command-line typically do not include the default choices the printer's PPD file. Use the
<b>ppdMarkDefaults</b>()
and
<b>cupsMarkOptions</b>()
functions in the CUPS library to apply the options to the PPD defaults and map any IPP attributes to the corresponding PPD options.
Use
<b>ppdFindMarkedChoice</b>()
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 <b>Duplex</b> PPD option:
<pre class="man">

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

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

    ppd_choice_t *choice = ppdFindMarkedChoice(ppd, "Duplex");
</pre>
<p>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.
<h2 class="title"><a name="LOG_MESSAGES">Log Messages</a></h2>
Messages sent to the standard error are generally stored in the printer's "printer-state-message" attribute and the current <b>ErrorLog</b> file.
Each line begins with a standard prefix:
<dl class="man">
<dt><b>ALERT: </b><i>message</i>
<dd style="margin-left: 5.0em">Sets the "printer-state-message" attribute and adds the specified message to the current <b>ErrorLog</b> using the "alert" log level.
<dt><b>ATTR: </b><i>attribute=value </i>[ <i>... attribute=value</i>]
<dd style="margin-left: 5.0em">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".
<dt><b>CRIT: </b><i>message</i>
<dd style="margin-left: 5.0em">Sets the "printer-state-message" attribute and adds the specified message to the current <b>ErrorLog</b> using the "critical" log level.
<dt><b>DEBUG: </b><i>message</i>
<dd style="margin-left: 5.0em">Adds the specified message to the current <b>ErrorLog</b> using the "debug" log level.
<b>DEBUG</b> messages are never stored in the "printer-state-message" attribute.
<dt><b>DEBUG2: </b><i>message</i>
<dd style="margin-left: 5.0em"><br>
Adds the specified message to the current <b>ErrorLog</b> using the "debug2" log level.
<b>DEBUG2</b> messages are never stored in the "printer-state-message" attribute.
<dt><b>EMERG: </b><i>message</i>
<dd style="margin-left: 5.0em">Sets the "printer-state-message" attribute and adds the specified message to the current <b>ErrorLog</b> using the "emergency" log level.
<dt><b>ERROR:</b><i> message</i>
<dd style="margin-left: 5.0em">Sets the "printer-state-message" attribute and adds the specified message to the current <b>ErrorLog</b> using the "error" log level.
<dt><b>INFO:</b><i> message</i>
<dd style="margin-left: 5.0em">Sets the "printer-state-message" attribute. If the current <b>LogLevel</b> is set to "debug2", also adds the specified message to the current <b>ErrorLog</b> using the "info" log level.
<dt><b>NOTICE:</b><i> message</i>
<dd style="margin-left: 5.0em">Sets the "printer-state-message" attribute and adds the specified message to the current <b>ErrorLog</b> using the "notice" log level.
<dt><b>PAGE:</b><i> page-number #-copies</i>
<dd style="margin-left: 5.0em"><dt><b>PAGE:</b><i> total #-pages</i>
<dd style="margin-left: 5.0em">Adds an entry to the current <b>PageLog</b>. The first form adds <i>#-copies</i> to the "job-media-sheets-completed" attribute. The second form sets the "job-media-sheets-completed" attribute to <i>#-pages</i>.
<dt><b>PPD:</b><i> Keyword=Value</i> [ <i>... KeywordN=Value</i> ]
<dd style="margin-left: 5.0em">Sets the named keywords in the printer's PPD file. This is typically used to update default option keywords such as <b>DefaultPageSize</b> and the various installable options in the PPD file.
<dt><b>STATE:</b><i> printer-state-reason </i>[ <i>... printer-state-reason</i> ]
<dd style="margin-left: 5.0em"><dt><b>STATE: +</b><i> printer-state-reason </i>[ <i>... printer-state-reason</i> ]
<dd style="margin-left: 5.0em"><dt><b>STATE: -</b><i> printer-state-reason </i>[ <i>... printer-state-reason</i> ]
<dd style="margin-left: 5.0em">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.
<dt><b>WARNING:</b><i> message</i>
<dd style="margin-left: 5.0em">Sets the "printer-state-message" attribute and adds the specified message to the current <b>ErrorLog</b> using the "warning" log level.
</dl>
<h2 class="title"><a name="ENVIRONMENT_VARIABLES">Environment Variables</a></h2>
The following environment variables are defined by the CUPS
server when executing the filter:
<dl class="man">
<dt><b>CHARSET</b>
<dd style="margin-left: 5.0em">The default text character set, typically "utf-8".
<dt><b>CLASS</b>
<dd style="margin-left: 5.0em">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.
<dt><b>CONTENT_TYPE</b>
<dd style="margin-left: 5.0em">The MIME media type associated with the submitted job file, for example "application/postscript".
<dt><b>CUPS_CACHEDIR</b>
<dd style="margin-left: 5.0em">The directory where semi-persistent cache files can be found and stored.
<dt><b>CUPS_DATADIR</b>
<dd style="margin-left: 5.0em">The directory where data files can be found.
<dt><b>CUPS_FILETYPE</b>
<dd style="margin-left: 5.0em">The type of file being printed: "job-sheet" for a banner page and "document"
for a regular print file.
<dt><b>CUPS_MAX_MESSAGE</b>
<dd style="margin-left: 5.0em">The maximum size of a message sent to <i>stderr</i>, including any leading prefix and the trailing newline.
<dt><b>CUPS_SERVERROOT</b>
<dd style="margin-left: 5.0em">The root directory of the server.
<dt><b>FINAL_CONTENT_TYPE</b>
<dd style="margin-left: 5.0em">The MIME media type associated with the output destined for the printer, for example "application/vnd.cups-postscript".
<dt><b>LANG</b>
<dd style="margin-left: 5.0em">The default language locale (typically C or en).
<dt><b>PATH</b>
<dd style="margin-left: 5.0em">The standard execution path for external programs that may be run by the filter.
<dt><b>PPD</b>
<dd style="margin-left: 5.0em">The full pathname of the PostScript Printer Description (PPD) file for this printer.
<dt><b>PRINTER</b>
<dd style="margin-left: 5.0em">The name of the printer.
<dt><b>RIP_CACHE</b>
<dd style="margin-left: 5.0em">The recommended amount of memory to use for Raster Image Processors (RIPs).
<dt><b>SOFTWARE</b>
<dd style="margin-left: 5.0em">The name and version number of the server (typically CUPS/<i>major.minor</i>).
<dt><b>TZ</b>
<dd style="margin-left: 5.0em">The timezone of the server.
<dt><b>USER</b>
<dd style="margin-left: 5.0em">The user executing the filter, typically "lp" or "root"; consult the <i>cups-files.conf</i> file for the current setting.
</dl>
<h2 class="title"><a name="CONFORMING_TO">Conforming To</a></h2>
While the filter interface is compatible with System V interface scripts, CUPS does not support System V interface scripts.
<h2 class="title"><a name="NOTES">Notes</a></h2>
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
<b>ippeveprinter</b>(1).
<p>CUPS filters are not meant to be run directly by the user.
Aside from the legacy System V interface issues (<i>argv[0]</i> 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
<b>cupsfilter</b>(8)
program to use the appropriate filters to do the conversions you need.
<h2 class="title"><a name="SEE_ALSO">See Also</a></h2>
<b>backend</b>(7),
<b>cups</b>(1),
<b>cups-files.conf</b>(5),
<b>cupsd</b>(8),
<b>cupsfilter</b>(8),
<br>
CUPS Online Help (<a href="http://localhost:631/help">http://localhost:631/help</a>)
<h2 class="title"><a name="COPYRIGHT">Copyright</a></h2>
Copyright &copy; 2007-2019 by Apple Inc.

</body>
</html>
Commit	Line	Data
c277f98c	1	<!DOCTYPE HTML>
94436c5a MS	2	<html>
	3	<!-- SECTION: Man Pages -->
	4	<head>
	5	<link rel="stylesheet" type="text/css" href="../cups-printable.css">
	6	<title>filter(7)</title>
	7	</head>
	8	<body>
	9	<h1 class="title">filter(7)</h1>
	10	<h2 class="title"><a name="NAME">Name</a></h2>
	11	filter - cups file conversion filter interface
	12	<h2 class="title"><a name="SYNOPSIS">Synopsis</a></h2>
c277f98c	13	<b>filter</b>
bfbd0197 MS	14	<i>job</i>
	15	<i>user</i>
	16	<i>title</i>
	17	<i>num-copies</i>
	18	<i>options</i>
	19	[
c277f98c MS	20	<i>filename</i>
c277f98c MS	21	]
2909c66c	22	<pre class="man">
bfbd0197 MS	23
	24	<b>#include <cups/cups.h></b>
	25
	26	<b>ssize_t cupsBackChannelRead</b>(<b>char *</b><i>buffer</i>, <b>size_t </b><i>bytes</i>,
	27	<b>double </b><i>timeout</i>);
	28
	29	<b>cups_sc_status_t cupsSideChannelDoRequest</b>(<b>cups_sc_command_t </b><i>command</i>,
	30	<b>char </b><i>data</i>, <b>int </b><i>datalen</i>,
	31	<b>double </b><i>timeout</i>);
	32
	33	<b>#include <cups/ppd.h></b>
	34
	35	<b>const char cupsGetOption</b>(<b>const char </b><i>name</i>, <b>int </b><i>num_options</i>,
	36	<b>cups_option_t *</b><i>options</i>);
	37
	38	<b>int cupsMarkOptions</b>(<b>ppd_file_t *</b><i>ppd</i>, <b>int </b><i>num_options</i>,
	39	<b>cups_option_t *</b><i>options</i>);
	40
	41	<b>int cupsParseOptions</b>(<b>const char *</b><i>arg</i>, <b>int </b><i>num_options</i>,
	42	<b>cups_option_t **</b><i>options</i>);
	43
	44	<b>ppd_choice_t ppdFindMarkedChoice</b>(<b>ppd_file_t </b><i>ppd</i>, <b>const char *</b><i>keyword</i>);
	45
	46	<b>void ppdMarkDefaults</b>(<b>ppd_file_t *</b><i>ppd</i>);
	47
	48	<b>ppd_file_t ppdOpenFile</b>(<b>const char </b><i>filename</i>);
	49	</pre>
94436c5a	50	<h2 class="title"><a name="DESCRIPTION">Description</a></h2>
bfbd0197 MS	51	The CUPS filter interface provides a standard method for adding support for new document types or printers to CUPS.
	52	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.
	53	<p>Filters <b>MUST</b> 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.
	54	All output <b>MUST</b> be sent to the standard output.
	55	Filters <b>MUST NOT</b> attempt to communicate directly with the printer, other processes, or other services.
	56	<p>The command name (<i>argv[0]</i>) is set to the name of the destination printer but is also available in the <b>PRINTER</b><i> environment variable.
	57	</i><h2 class="title"><a name="OPTIONS">Options</a></h2>
	58	Options are passed in <i>argv[5]</i> and are encoded from the corresponding IPP attributes used when the job was submitted. Use the
	59	<b>cupsParseOptions</b>()
	60	function to load the options into a <b>cups_option_t</b> array and the
	61	<b>cupsGetOption</b>()
	62	function to get the value of a specific attribute.
dd3fdd2c	63	Be careful to look for common aliases of IPP attributes such as "landscape" for the IPP "orientation-requested" attribute.
bfbd0197 MS	64	<p>Options passed on the command-line typically do not include the default choices the printer's PPD file. Use the
	65	<b>ppdMarkDefaults</b>()
	66	and
	67	<b>cupsMarkOptions</b>()
	68	functions in the CUPS library to apply the options to the PPD defaults and map any IPP attributes to the corresponding PPD options.
	69	Use
	70	<b>ppdFindMarkedChoice</b>()
	71	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 <b>Duplex</b> PPD option:
2909c66c	72	<pre class="man">
bfbd0197 MS	73
	74	ppd_file_t *ppd = ppdOpenFile(getenv("PPD"));
	75	cups_option_t *options = NULL;
	76	int num_options = cupsParseOptions(argv[5], 0, &options);
	77
	78	ppdMarkDefaults(ppd);
	79	cupsMarkOptions(ppd, num_options, options);
	80
	81	ppd_choice_t *choice = ppdFindMarkedChoice(ppd, "Duplex");
	82	</pre>
	83	<p>Raster filters should use option choices set through the raster page header, as those reflect the options in effect for a given page.
	84	Options specified on the command-line determine the default values for the entire job, which can be overridden on a per-page basis.
94436c5a	85	<h2 class="title"><a name="LOG_MESSAGES">Log Messages</a></h2>
bfbd0197	86	Messages sent to the standard error are generally stored in the printer's "printer-state-message" attribute and the current <b>ErrorLog</b> file.
94436c5a	87	Each line begins with a standard prefix:
2909c66c MS	88	<dl class="man">
	89	<dt><b>ALERT: </b><i>message</i>
	90	<dd style="margin-left: 5.0em">Sets the "printer-state-message" attribute and adds the specified message to the current <b>ErrorLog</b> using the "alert" log level.
	91	<dt><b>ATTR: </b><i>attribute=value </i>[ <i>... attribute=value</i>]
	92	<dd style="margin-left: 5.0em">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:
94436c5a MS	93	"auth-info-required", "marker-colors", "marker-high-levels", "marker-levels",
	94	"marker-low-levels", "marker-message", "marker-names", "marker-types",
	95	"printer-alert", and "printer-alert-description".
2909c66c MS	96	<dt><b>CRIT: </b><i>message</i>
	97	<dd style="margin-left: 5.0em">Sets the "printer-state-message" attribute and adds the specified message to the current <b>ErrorLog</b> using the "critical" log level.
	98	<dt><b>DEBUG: </b><i>message</i>
	99	<dd style="margin-left: 5.0em">Adds the specified message to the current <b>ErrorLog</b> using the "debug" log level.
bfbd0197	100	<b>DEBUG</b> messages are never stored in the "printer-state-message" attribute.
2909c66c MS	101	<dt><b>DEBUG2: </b><i>message</i>
2909c66c MS	102	<dd style="margin-left: 5.0em"><br>
bfbd0197 MS	103	Adds the specified message to the current <b>ErrorLog</b> using the "debug2" log level.
bfbd0197 MS	104	<b>DEBUG2</b> messages are never stored in the "printer-state-message" attribute.
2909c66c MS	105	<dt><b>EMERG: </b><i>message</i>
	106	<dd style="margin-left: 5.0em">Sets the "printer-state-message" attribute and adds the specified message to the current <b>ErrorLog</b> using the "emergency" log level.
	107	<dt><b>ERROR:</b><i> message</i>
	108	<dd style="margin-left: 5.0em">Sets the "printer-state-message" attribute and adds the specified message to the current <b>ErrorLog</b> using the "error" log level.
	109	<dt><b>INFO:</b><i> message</i>
	110	<dd style="margin-left: 5.0em">Sets the "printer-state-message" attribute. If the current <b>LogLevel</b> is set to "debug2", also adds the specified message to the current <b>ErrorLog</b> using the "info" log level.
	111	<dt><b>NOTICE:</b><i> message</i>
	112	<dd style="margin-left: 5.0em">Sets the "printer-state-message" attribute and adds the specified message to the current <b>ErrorLog</b> using the "notice" log level.
	113	<dt><b>PAGE:</b><i> page-number #-copies</i>
	114	<dd style="margin-left: 5.0em"><dt><b>PAGE:</b><i> total #-pages</i>
	115	<dd style="margin-left: 5.0em">Adds an entry to the current <b>PageLog</b>. The first form adds <i>#-copies</i> to the "job-media-sheets-completed" attribute. The second form sets the "job-media-sheets-completed" attribute to <i>#-pages</i>.
	116	<dt><b>PPD:</b><i> Keyword=Value</i> [ <i>... KeywordN=Value</i> ]
	117	<dd style="margin-left: 5.0em">Sets the named keywords in the printer's PPD file. This is typically used to update default option keywords such as <b>DefaultPageSize</b> and the various installable options in the PPD file.
	118	<dt><b>STATE:</b><i> printer-state-reason </i>[ <i>... printer-state-reason</i> ]
	119	<dd style="margin-left: 5.0em"><dt><b>STATE: +</b><i> printer-state-reason </i>[ <i>... printer-state-reason</i> ]
	120	<dd style="margin-left: 5.0em"><dt><b>STATE: -</b><i> printer-state-reason </i>[ <i>... printer-state-reason</i> ]
	121	<dd style="margin-left: 5.0em">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.
	122	<dt><b>WARNING:</b><i> message</i>
	123	<dd style="margin-left: 5.0em">Sets the "printer-state-message" attribute and adds the specified message to the current <b>ErrorLog</b> using the "warning" log level.
	124	</dl>
94436c5a MS	125	<h2 class="title"><a name="ENVIRONMENT_VARIABLES">Environment Variables</a></h2>
	126	The following environment variables are defined by the CUPS
	127	server when executing the filter:
2909c66c MS	128	<dl class="man">
	129	<dt><b>CHARSET</b>
	130	<dd style="margin-left: 5.0em">The default text character set, typically "utf-8".
	131	<dt><b>CLASS</b>
	132	<dd style="margin-left: 5.0em">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.
	133	<dt><b>CONTENT_TYPE</b>
	134	<dd style="margin-left: 5.0em">The MIME media type associated with the submitted job file, for example "application/postscript".
	135	<dt><b>CUPS_CACHEDIR</b>
	136	<dd style="margin-left: 5.0em">The directory where semi-persistent cache files can be found and stored.
	137	<dt><b>CUPS_DATADIR</b>
	138	<dd style="margin-left: 5.0em">The directory where data files can be found.
	139	<dt><b>CUPS_FILETYPE</b>
	140	<dd style="margin-left: 5.0em">The type of file being printed: "job-sheet" for a banner page and "document"
bfbd0197	141	for a regular print file.
2909c66c MS	142	<dt><b>CUPS_MAX_MESSAGE</b>
	143	<dd style="margin-left: 5.0em">The maximum size of a message sent to <i>stderr</i>, including any leading prefix and the trailing newline.
	144	<dt><b>CUPS_SERVERROOT</b>
	145	<dd style="margin-left: 5.0em">The root directory of the server.
	146	<dt><b>FINAL_CONTENT_TYPE</b>
	147	<dd style="margin-left: 5.0em">The MIME media type associated with the output destined for the printer, for example "application/vnd.cups-postscript".
	148	<dt><b>LANG</b>
	149	<dd style="margin-left: 5.0em">The default language locale (typically C or en).
	150	<dt><b>PATH</b>
	151	<dd style="margin-left: 5.0em">The standard execution path for external programs that may be run by the filter.
	152	<dt><b>PPD</b>
	153	<dd style="margin-left: 5.0em">The full pathname of the PostScript Printer Description (PPD) file for this printer.
	154	<dt><b>PRINTER</b>
	155	<dd style="margin-left: 5.0em">The name of the printer.
	156	<dt><b>RIP_CACHE</b>
	157	<dd style="margin-left: 5.0em">The recommended amount of memory to use for Raster Image Processors (RIPs).
	158	<dt><b>SOFTWARE</b>
	159	<dd style="margin-left: 5.0em">The name and version number of the server (typically CUPS/<i>major.minor</i>).
	160	<dt><b>TZ</b>
	161	<dd style="margin-left: 5.0em">The timezone of the server.
	162	<dt><b>USER</b>
	163	<dd style="margin-left: 5.0em">The user executing the filter, typically "lp" or "root"; consult the <i>cups-files.conf</i> file for the current setting.
	164	</dl>
bfbd0197	165	<h2 class="title"><a name="CONFORMING_TO">Conforming To</a></h2>
e67e2f9e	166	While the filter interface is compatible with System V interface scripts, CUPS does not support System V interface scripts.
bfbd0197	167	<h2 class="title"><a name="NOTES">Notes</a></h2>
87030afb MS	168	CUPS printer drivers and backends are deprecated and will no longer be supported in a future feature release of CUPS.
	169	Printers that do not support IPP can be supported using applications such as
	170	<b>ippeveprinter</b>(1).
	171	<p>CUPS filters are not meant to be run directly by the user.
8072030b	172	Aside from the legacy System V interface issues (<i>argv[0]</i> 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.
bfbd0197 MS	173	Unless you are a developer and know what you are doing, please do not run filters directly.
bfbd0197 MS	174	Instead, use the
87030afb	175	<b>cupsfilter</b>(8)
bfbd0197	176	program to use the appropriate filters to do the conversions you need.
94436c5a	177	<h2 class="title"><a name="SEE_ALSO">See Also</a></h2>
87030afb MS	178	<b>backend</b>(7),
87030afb MS	179	<b>cups</b>(1),
696f74ae MS	180	<b>cups-files.conf</b>(5),
696f74ae MS	181	<b>cupsd</b>(8),
87030afb	182	<b>cupsfilter</b>(8),
94436c5a	183	<br>
bfbd0197	184	CUPS Online Help (<a href="http://localhost:631/help">http://localhost:631/help</a>)
94436c5a	185	<h2 class="title"><a name="COPYRIGHT">Copyright</a></h2>
87030afb	186	Copyright © 2007-2019 by Apple Inc.
94436c5a MS	187
	188	</body>
	189	</html>