What is LD_LIBRARY_PATH and how to use it?

I take part in developing a Java project, which uses some C++ components, thus I need Jacob.dll. (on Windows 7)

I keep getting java.lang.UnsatisfiedLinkError: no JacobDB in java.library.path no matter where I put Jacob.dll....

I looked for possible decisions and the one that I haven't tried so far is setting the LD_LIBRARY_PATH variable, pointing at the .dll file.

I have little experience and I'm not familiar with what should be the meaning and usage of that variable - can you help me?

Solution 1:

LD_LIBRARY_PATH is the predefined environmental variable in Linux/Unix which sets the path which the linker should look in to while linking dynamic libraries/shared libraries.

LD_LIBRARY_PATH contains a colon separated list of paths and the linker gives priority to these paths over the standard library paths /lib and /usr/lib. The standard paths will still be searched, but only after the list of paths in LD_LIBRARY_PATH has been exhausted.

The best way to use LD_LIBRARY_PATH is to set it on the command line or script immediately before executing the program. This way the new LD_LIBRARY_PATH isolated from the rest of your system.

Example Usage:

$ export LD_LIBRARY_PATH="/list/of/library/paths:/another/path"
$ ./program

Since you talk about .dll you are on a windows system and a .dll must be placed at a path which the linker searches at link time, in windows this path is set by the environmental variable PATH, So add that .dll to PATH and it should work fine.

Solution 2:

Typically you must set java.library.path on the JVM's command line:

java -Djava.library.path=/path/to/my/dll -cp /my/classpath/goes/here MainClass

Solution 3:

LD_LIBRARY_PATH is Linux specific and is an environment variable pointing to directories where the dynamic loader should look for shared libraries.

Try to add the directory where your .dll is in the PATH variable. Windows will automatically look in the directories listed in this environment variable. LD_LIBRARY_PATH probably won't solve the problem (unless the JVM uses it - I do not know about that).

Solution 4:

LD_LIBRARY_PATH is the default library path which is accessed to check for available dynamic and shared libraries. It is specific to linux distributions.

It is similar to environment variable PATH in windows that linker checks for possible implementations during linking time.