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backend

cups backend transmission interfaces


  1. backend.1.man
  2. backend.7.man


1. backend.1.man

Manpage of backend

backend

Section: Easy Software Products (1)
Updated: Common UNIX Printing System
Index Return to Main Contents
 

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. Starting with CUPS 1.1.22, any authentication information in argv[0] will be removed, so backend developers are urged to use the DEVICE_URI environment variable whenever authentication information is required.  

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 and for backends that require any authentication information which is not included in argv[0].
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.
 

SEE ALSO

cupsd(8), filter(1) CUPS Interface Design Description, CUPS Software Administrators Manual, CUPS Software Programmers Manual, http://localhost:631/documentati  

COPYRIGHT

Copyright 1993-2005 by Easy Software Products, All Rights Reserved.


 

Index

NAME
SYNOPSIS
DESCRIPTION
ENVIRONMENT VARIABLES
SEE ALSO
COPYRIGHT

This document was created by man2html using the manual pages.
Time: 17:30:20 GMT, October 23, 2013

2. backend.7.man

Manpage of backend

backend

Section: Apple Inc. (7)
Updated: CUPS
Index Return to Main Contents

 

NAME

backend - cups backend transmission interfaces

 

SYNOPSIS

backend
backend job user title num-copies options [ filename ]

 

DESCRIPTION

Backends are a special type of filter(7) which is used to send print data to and discover different devices on the system.

Like filters, 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 as required by the physical interface.

The command name (argv[0]) is set to the device URI of the destination printer. Starting with CUPS 1.1.22, any authentication information in argv[0] is removed, so backend developers are urged to use the DEVICE_URI environment variable whenever authentication information is required. The CUPS API includes a cupsBackendDeviceURI function for retrieving the correct device URI.

Back-channel data from the device should be relayed to the job filters by writing to file descriptor 3. The CUPS API includes the cupsBackChannelWrite function for this purpose.

 

DEVICE DISCOVERY

When run with no arguments, the backend should list the devices and schemes it supports or is advertising to stdout. The output consists of zero or more lines consisting of any of the following forms:

    device-class scheme "Unknown" "device-info"
    device-class device-uri "device-make-and-model" "device-info"
    device-class device-uri "device-make-and-model" "device-info" "device-id"
    device-class device-uri "device-make-and-model" "device-info" "device-id" "device-location"

The device-class field is one of the following values:

direct

The device-uri refers to a specific direct-access device with no options, such as a parallel, USB, or SCSI device.

file

The device-uri refers to a file on disk.

network

The device-uri refers to a networked device and conforms to the general form for network URIs.

serial

The device-uri refers to a serial device with configurable baud rate and other options. If the device-uri contains a baud value, it represents the maximum baud rate supported by the device.

The scheme field provides the URI scheme that is supported by the backend. Backends should use this form only when the backend supports any URI using that scheme. The device-uri field specifies the full URI to use when communicating with the device.

The device-make-and-model field specifies the make and model of the device, e.g. "Acme Foojet 2000". If the make and model is not known, you must report "Unknown".

The device-info field specifies additional information about the device. Typically this includes the make and model along with the port number or network address, e.g. "Acme Foojet 2000 USB #1".

The optional device-id field specifies the IEEE-1284 device ID string for the device, which is used to select a matching driver.

The optional device-location field specifies the physical location of the device, which is often used to pre-populate the printer-location attribute when adding a printer.

 

PERMISSIONS

Backends without world execute permissions are run as the root user. Otherwise, the backend is run using the unprivileged user account, typically "lp".

 

EXIT CODES

The following exit codes are defined for backends; C API constants defined in the <cups/backend.h> header file are defined in parenthesis:

0 (CUPS_BACKEND_OK)

The print file was successfully transmitted to the device or remote server.

1 (CUPS_BACKEND_FAILED)

The print file was not successfully transmitted to the device or remote server. The scheduler will respond to this by canceling the job, retrying the job, or stopping the queue depending on the state of the error-policy attribute.

2 (CUPS_BACKEND_AUTH_REQUIRED)

The print file was not successfully transmitted because valid authentication information is required. The scheduler will respond to this by holding the job and adding the authentication-required job-reasons keyword.

3 (CUPS_BACKEND_HOLD)

The print file was not successfully transmitted because it cannot be printed at this time. The scheduler will respond to this by holding the job.

4 (CUPS_BACKEND_STOP)

The print file was not successfully transmitted because it cannot be printed at this time. The scheduler will respond to this by stopping the queue.

5 (CUPS_BACKEND_CANCEL)

The print file was not successfully transmitted because one or more attributes are not supported. The scheduler will respond to this by canceling the job.

All other exit code values are reserved.

 

SEE ALSO

cupsd(8), cupsd.conf(5), filter(7),
http://localhost:631/help

 

COPYRIGHT

Copyright 2007-2009 by Apple Inc.


 

Index

NAME
SYNOPSIS
DESCRIPTION
DEVICE DISCOVERY
PERMISSIONS
EXIT CODES
SEE ALSO
COPYRIGHT

This document was created by man2html using the manual pages.
Time: 17:30:20 GMT, October 23, 2013

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