bionic (5) sane-dll.5.gz

NAME

       sane-dll - SANE dynamic backend loader

DESCRIPTION

       The  sane-dll  library  implements  a  SANE  (Scanner Access Now Easy) backend that provides access to an
       arbitrary number of other SANE backends.  These backends  may  either  be  pre-loaded  at  the  time  the
       sane-dll  library  is built or, on systems that support dynamic loading of shared libraries, the backends
       may be loaded at runtime.  In the  latter  case,  adding  support  for  a  new  backend  simply  involves
       installing  the  relevant library in @LIBDIR@ and adding an entry to the dll.conf configuration file.  In
       other words, no applications need to be modified or recompiled to add support for new devices.

DEVICE NAMES

       This backend expects device names of the form:

              backend:device

       Where backend is the name of the backend and device is the name of the device in this backend that should
       be  addressed.  If the device name does not contain a colon (:), then the entire string is treated as the
       device string for the  default  backend.   The  default  backend  is  the  backend  listed  last  in  the
       configuration file (see below) or the first pre-loaded backend (if any).

CONFIGURATION

       The  contents of the dll.conf file is a list of backend names that may be loaded dynamically upon demand.
       Empty lines are ignored, also everything after a hash mark (#). A  sample  configuration  file  is  shown
       below:

              net
              # this is a comment
              pnm
              mustek

       It  is  also  possible to add a file in @CONFIGDIR@/dll.d that contains the list of backends to be added.
       Backends mentioned in a file included in this directory will be  added  before  any  backends  listed  in
       dll.conf.   Files  in  @CONFIGDIR@/dll.d can be freely named. They shall follow the format conventions as
       apply for dll.conf.

       Note that backends that were pre-loaded when building this library do not  have  to  be  listed  in  this
       configuration  file.   That  is,  if  a  backend was preloaded, then that backend will always be present,
       regardless of whether it's listed in the configuration file or not.

       The list of preloaded backends is determined by macro PRELOADABLE_BACKENDS in file backend/Makefile.in of
       the  SANE  source  code  distribution.   After  changing  the  value  of  this  macro, it is necessary to
       reconfigure, rebuild, and reinstall SANE for the change to take effect.

       Aliases are defined in the config file dll.aliases.  It can contain entries of the form

              alias SomeName SaneDeviceName
              alias "Some Name" SaneDeviceName
              hide SaneDeviceName

       For example:

              alias Epson net:somehost:epson:/dev/sgX
              alias "Siemens ST400" st400:/dev/sgY
              hide net:somehost:pnm:0
              hide net:somehost:pnm:1
              alias "Read from file" pnm:0
              hide pnm:1

       Aliased device names are automatically hidden.

       The idea is that users don't have to  deal  with  complicated  device  names  (especially  for  networked
       devices),  and  to  hide  other  exported devices which might confuse them. Note that a hidden device can
       still be accessed if the device name is known, it just doesn't appear on the list.

FILES

       @CONFIGDIR@/dll.aliases
              The list of aliased or hidden backends.

       @CONFIGDIR@/dll.conf
              The backend configuration file (see also description of SANE_CONFIG_DIR below).

       @LIBDIR@/libsane-dll.a
              The static library implementing this backend.

       @LIBDIR@/libsane-dll.so
              The shared library implementing this backend (present on systems that support dynamic loading).

ENVIRONMENT

       SANE_CONFIG_DIR
              This environment variable specifies the list of directories that  may  contain  the  configuration
              file.   Under UNIX, the directories are separated by a colon (`:'), under OS/2, they are separated
              by a semi-colon (`;').  If this variable is not set, the configuration file  is  searched  in  two
              default  directories:  first, the current working directory (".") and then in @CONFIGDIR@.  If the
              value of the environment variable ends with the directory separator character,  then  the  default
              directories  are  searched  after  the  explicitly  specified  directories.   For example, setting
              SANE_CONFIG_DIR to "/tmp/config:" would result in directories "tmp/config", ".", and "@CONFIGDIR@"
              being searched (in this order).

       SANE_DEBUG_DLL
              If  the  library  was  compiled with debug support enabled, this environment variable controls the
              debug level for this backend.  E.g., a value of 128 requests  all  debug  output  to  be  printed.
              Smaller levels reduce verbosity.

              Value  Description
              0      print severe errors only
              1      print normal errors and important messages
              2      print normal messages
              3      print debugging messages
              4      print everything

              Example: export SANE_DEBUG_DLL=3

SEE ALSO

       sane(7), scanimage(1), sane-"backendname"(5)

AUTHOR

       David Mosberger

@PACKAGEVERSION@                                   13 Jul 2008                                       sane-dll(5)