sane-dll(5) SANE Scanner Access Now Easy sane-dll(5)
sane-dll - SANE dynamic backend loader
The sane-dll library implements a SANE (Scanner Access Now Easy) backend that provides access to an arbitrary number of other SANE back-
ends. 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 /usr/lib64/sane 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.
This backend expects device names of the form:
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).
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:
# this is a comment
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 distribu-
tion. 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
alias Epson net:somehost:epson:/dev/sgX
alias "Siemens ST400" st400:/dev/sgY
alias "Read from file" pnm:0
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 of aliased or hidden backends.
The backend configuration file (see also description of SANE_CONFIG_DIR below).
The static library implementing this backend.
The shared library implementing this backend (present on systems that support dynamic loading).
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 configura-
tion file is searched in two default directories: first, the current working directory (".") and then in /etc/sane.d. If the value
of the environment variable ends with the directory separator character, then the default directories are searched after the explic-
itly specified directories. For example, setting SANE_CONFIG_DIR to "/tmp/config:" would result in directories "tmp/config", ".",
and "/etc/sane.d" being searched (in this order).
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.
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
sane(7), scanimage(1), sane-"backendname"(5)
13 Jul 2008 sane-dll(5)