How to Prioritize Library Preference During Linking?

Specify Library Preference During Linking

In a scenario where a specific shared library needs to be used during linking, but a system library with the same name exists, it's useful to control the preference and ensure the intended library takes precedence. Here's how to achieve this.

LD_LIBRARY_PATH

One solution is to modify the LD_LIBRARY_PATH environment variable, which lists the directories where the linker searches for shared libraries. By adding the path to the intended library to the start or end of LD_LIBRARY_PATH, the linker will prioritize it over the system library. However, caution is advised as misconfigurations can introduce security risks or performance issues.

-Wl,-rpath

Alternatively, the -Wl,-rpath compiler option can be used to specify the runtime library search path. By adding -Wl,-rpath,$(DEFAULT_LIB_INSTALL_PATH), the linker will search the specified directory for libraries before searching in standard directories. This option is a temporary solution that overrides the default search path for the specific application.

Temporary Path Modification

Immediate manipulation of library preferences can be achieved by using LD_LIBRARY_PATH on the fly during command execution. By setting LD_LIBRARY_PATH=/some/custom/dir before running the program, the linker temporarily searches the specified directory for libraries.

Checking Library Resolution

To verify which libraries are being linked, use ldconfig -p | grep libpthread to list known libraries. To check which libraries are used by an application, run ldd foo to view resolved dependencies.

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