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filter(7) | Apple Inc. | filter(7) |
NAME¶
filter - cups file conversion filter interfaceSYNOPSIS¶
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.WARNING¶
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.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 specified 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 mapping, 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
-
- ATTR: attribute=value [attribute=value]
-
- CRIT: message
-
- DEBUG: message
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- DEBUG2: message
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- EMERG: message
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- ERROR: message
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- INFO: message
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- NOTICE: message
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- PAGE: page-number #-copies
- PAGE: total #-pages
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- PPD: Keyword=Value ... KeywordN=Value
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- STATE: printer-state-reason [printer-state-reason ...]
- STATE: + printer-state-reason [printer-state-reason ...]
- STATE: - printer-state-reason [printer-state-reason ...]
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- WARNING: message
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ENVIRONMENT VARIABLES¶
The following environment variables are defined by the CUPS server when executing the filter:- CHARSET
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- CLASS
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- CONTENT_TYPE
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- CUPS_CACHEDIR
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- CUPS_DATADIR
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- CUPS_FILETYPE
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- CUPS_MAX_MESSAGE
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- CUPS_SERVERROOT
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- DEVICE_URI
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- FINAL_CONTENT_TYPE
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- LANG
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- PATH
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- PPD
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- PRINTER
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- RIP_CACHE
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- SOFTWARE
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- TZ
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- USER
-
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), cupsfilter(8),COPYRIGHT¶
Copyright 2007-2013 by Apple Inc.CUPS | 18 May 2012 |