  /
  |
  +--- etc
  |     |
  |     +--- caps                        (CAPS Configuration Directory)
  |     |      |
  |     |      +--- drivers              (CAPS Printer Driver Configuration Directory)
  |
  +--- usr
  |     |
  |     +--- bin                         (Tools Directory)
  |     |
  |     +--- lib                         (Library Directory)
  |     |
  |     +--- libexec
  |     |      |
  |     |      +--- caps                 (CAPS Printer Driver Executables Directory)
  |     |      |
  |     |
  |     +--- include                     (Header File Directory)
  |     |
  |     +--- sbin                        (Service Executables Directory)
  |     |
  |     +--- share
  |     |      |
  |     |      +--- caps
  |     |      |     |
  |     |      |     +--- drivers        (CAPS Printer Driver Database Directory)
  |
  +--- var
  |     |
  |     +--- lib
  |     |     |
  |     |     +--- caps                  (CAPS Printer Device Database Directory)
  |     |     |      |
  |     |     |      +--- printer_dhfgez (CAPS Printer Device Parameter Directory)
  |     |
  |     +--- spool
  |     |     |
  |     |     +--- caps                  (CAPS Document Storage Directory)
  |     |     |

Note: The printer_dhfgez" in the "CAPS Device Parameter Directory is an example here. Refer CAPS Printer Device Parameter Directory for more details.

CAPS Configuration Directory

Directory contains basic configuration INI files for all CAPS universe components.

The CAPS Printer Driver Configuration Directory is also located here as a subdirectory.

Refer Setup the CAPS Configuration Directory as well.

CAPS Printer Driver Database Directory

This directory provides Device Description INI files and thus, forms a database about installed/supported printer devices. For each printer device one of such file exists (if the suitable printer driver is installed).

Each INI file provides information about the supported printer device to enable CAPS to identify the suitable printer driver for it.

Each printer driver installs here its own set of Device Description INI files for all printer devices it supports.

It's not possible to share Device Description INI files, each of it is unique and describes exactly one printer device.

But it is possible to have more than one printer driver supporting a specific printer device. In this case more than one INI file exists, matching the same printer device, but refers to different printer drivers. For example, a printer device able to work with a vendor specific data protocol or PCL can be run with its native printer driver or the generic PCL printer driver. In this case the first printer device match always wins.

All INI files in this directory should be owned by root.

Refer Setup the CAPS Driver Database Directory as well.

CAPS Printer Device Parameter Directory

This is a unique subdirectory on a per printer device in the CAPS Printer Device Database Directory. It contains specific configurations for exactly one printer device.
All files from this directory are read-in and the read-in order follows the Sorted INI.

Note: The capsprndir helper tool can retrieve the directory specific for a printer device.

CAPS Document Storage Directory

Directory used to temporarily store the documents to print and other printing related files. This directory needs to be writable (guess why) and large enough to hold the files until they are printed.

Note: You will see files in this directory only, if debugging is enabled. Else all files are invisible and get removed in a self-removing manner automatically if no longer used.; This directory must be writable and should use a filesystem which supports invisible files (refer O_TMPFILE flag in the open() syscall or caps_helper_invisible_file_create()), it must be owned by lp and group lp.

Refer Setup CAPS Document Storage Directory as well.

CAPS Printer Driver Configuration Directory

This directory provides Driver Feature Configuration INI files for some printer driver default settings if appropriate. If settings do not match a printer device requirement, they can be overwritten on a printer device specific base (refer CAPS Printer Device Parameter Directory).

Each printer driver installs here its own driver specific configuration INI file with its default settings (if any). Its file name is referenced in the Device Description INI file. This driver specific configuration INI file can be shared between all driver users (e.g. printing devices), because it's read-only.

Refer Setup the CAPS Driver Configuration Directory as well.

CAPS Printer Driver Executables Directory

This directory collects the installed printer driver executables. They are referenced in the Device Description INI files in the CAPS Printer Driver Database Directory and thus, CAPS is able to run the printing device's matching printer driver.

Each printer driver installs here its own executable. It can be shared between multiple printer devices.

All executable files in this directory should be owned by root.

Refer Setup CAPS Driver Executables Directory as well.

CAPS Printer Device Database Directory

This directory stores the Printer Device Database, maintained by CAPS. And it contains printer device specific parameters in printer device unique subdirectories (refer CAPS Printer Device Parameter Directory for details).

Refer Setup the CAPS Device Database Directory as well.