sane-dll(5) SANE Scanner Access Now Easy sane-dll(5)NAMEsane-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 /usr/free-
ware/lib32/sane and adding an entry to the dll.conf con-
figuration 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
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
/usr/freeware/etc/sane.d/dll.aliases
The list of aliased or hidden backends.
/usr/freeware/etc/sane.d/dll.conf
The backend configuration file (see also descrip-
tion of SANE_CONFIG_DIR below).
/usr/freeware/lib32/sane/libsane-dll.a
The static library implementing this backend.
/usr/freeware/lib32/sane/libsane-dll.so
The shared library implementing this backend (pre-
sent 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 /usr/freeware/etc/sane.d. If the
value of the environment variable ends with the
directory separator character, then the default
directories are searched after the explicitly spec-
ified directories. For example, setting SANE_CON-
FIG_DIR to "/tmp/config:" would result in directo-
ries "tmp/config", ".", and "/usr/free-
ware/etc/sane.d" 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 ALSOsane(7), scanimage(1), sane-"backendname"(5)
AUTHOR
David Mosberger
sane-backends 1.0.12 4 Dec 2002 sane-dll(5)
