ldd

LDD is an acronym that can refer to several concepts in different fields, but in computing it most commonly denotes the Linux command ldd, which is used to display the shared library dependencies of an executable or script.

The ldd command prints the shared objects required to run a program and, when possible, shows the absolute path to each library. It is a utility used for debugging runtime dependencies, diagnosing library-mismatch errors, and understanding how an executable is linked. Typical usage is to run ldd followed by a path to the binary, for example ldd ./program.

In terms of implementation, ldd on most Linux systems is a lightweight utility that invokes the dynamic linker in a controlled way to reveal which libraries are loaded by the target binary. The exact presentation of the output can vary with the libc implementation and distribution, but the common result is a list of libraries with their paths and memory addresses. Some environments provide ldd as a compiled binary, while others implement it as a shell script that interacts with the dynamic linker.

Security considerations accompany the use of ldd. Running ldd on untrusted binaries can be risky because the dependency discovery process may execute code from the binary or linked libraries. Safer approaches for static analysis include using tools that inspect the binary without execution, such as readelf -d or objdump -p, to examine dynamic sections and needed libraries.

Other uses of the acronym LDD exist in different domains, but this article focuses on the Linux command. See also dynamic linker, shared library, ld.so, readelf, and objdump.