ldconfig

ldconfig is a standard utility in Linux and other Unix-like systems that configures the dynamic linker run-time bindings. It updates and maintains the cache used by the dynamic linker to locate shared libraries, /etc/ld.so.cache, and creates the necessary symbolic links for library names to their actual files. The tool is typically run as root after installing new libraries to ensure correct runtime linking.

ldconfig reads the directories listed in /etc/ld.so.conf and in files under /etc/ld.so.conf.d, plus common library directories such as /lib, /usr/lib, and their architecture-specific variants like /lib64. It scans for shared library files with the .so suffix, resolves their SONAMEs, and builds a mapping from names to absolute paths, updating the cache accordingly. By updating the cache, the dynamic linker can quickly locate libraries at program startup without scanning directories.

Usage and availability: The tool is part of the glibc package on Linux. It is located in /sbin/ldconfig and may be installed or located in /usr/sbin. Typical usage includes ldconfig -p to display the current cache contents and ldconfig -v for verbose output. In general, running ldconfig without arguments updates the cache based on the system configuration.