LTDL_LIBRARY_PATH和LD_LIBRARY_PATH有什么区别？

Question

In compiling and linking C and C++ code, what is the purpose of LTDL_LIBRARY_PATH and LD_LIBRARY_PATH environment variables? In addition what is the difference between them?

Thanks

Answer 1

LTDL_LIBRARY_PATH sets a library search path for the libtool library , a helper/portability library for using shared libraries. That library will search the directories in this path before searching LD_LIBRARY_PATH which is an environment variable that sets a search path for the system's shared library loader.

From the libtool documentation :

If libltdl cannot find the library and the file name filename does not have a directory component it will additionally look in the following search paths for the module (in the following order):

• user-defined search path: This search path can be changed by the program using the functions lt_dlsetsearchpath , lt_dladdsearchdir and lt_dlinsertsearchdir .
• libltdl 's search path: This search path is the value of the environment variable LTDL_LIBRARY_PATH .
• system library search path: The system dependent library search path (eg on GNU/Linux it is LD_LIBRARY_PATH )

As mentioned above, LD_LIBRARY_PATH is an environment variable that the system will use to search for shared libraries.