The default search paths used by the runtime linker are /lib and /usr/lib for 32–bit application. For 64–bit applications, the default search paths are /lib/64 and /usr/lib/64. These search paths can be administered using a runtime configuration file created by the crle(1) utility. This file is often a useful aid for establishing search paths for applications that have not been built with the correct runpaths.
A configuration file can be constructed in the default location /var/ld/ld.config, for 32–bit applications, or /var/ld/64/ld.config, for 64–bit applications. This file affects all applications of the respective type on a system. Configuration files can also be created in other locations, and the runtime linker's LD_CONFIG environment variable used to select these files. This latter method is useful for testing a configuration file before installing the file in the default location.