NAME
backend - cups backend transmission interfaces  
SYNOPSIS
backend job user title num-copies options [ filename ]  
DESCRIPTION
The CUPS backend interface provides a standard method for sending document files to different physical interfaces.

Backends 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 if required by the physical interface.

The command name (argv[0]) is set to the device URI of the destination printer.  
ENVIRONMENT VARIABLES
The following environment variables are defined by the CUPS server when executing the backend:

CHARSET

    The default text character set (typically us-ascii or iso-8859-1). 
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/postscript). 
CUPS_DATADIR

    The directory where data files can be found. 
CUPS_SERVERROOT

    The root directory of the server. 
DEVICE_URI

    The device-uri associated with the printer; this is provided for shell scripts which may not be able to get the passed argv[0] string. 
LANG

    The default language locale (typically C or en). 
PATH

    The standard execution path for external programs that may be run by the backend. 
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/1.1). 
TZ

    The timezone of the server. 
USER

    The user executing the backend, typically root; consult the cupsd.conf file for the current setting.