Section: SANE Scanner Access Now Easy (5)
Updated: 13 Jul 2008
sane-dll - SANE dynamic backend loader
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
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
and adding an entry to the
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:
is the name of the backend and
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
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
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
It is also possible to add a file in
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
can be freely named. They shall follow the format conventions as apply for
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
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
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
The list of aliased or hidden backends.
The backend configuration file (see also description of
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 configuration file
is searched in two default directories: first, the current working
directory (".") and then in
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
to "/tmp/config:" would result in directories
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