LD_PRELOAD loads symbols from dynamic libraries before "real" dynamic linking happens. This can be used to inject or replace certain symbols with your own defin

LD_PRELOAD loads symbols from dynamic libraries before "real" dynamic linking happens. This can be used to inject or replace certain symbols with your own definitions. The classic LD_PRELOAD trick is to replace malloc and free with your own functions that contain some kind of instrumentation for debugging/profiling purposes. Tinkering with LD_PRELOAD (and LD_LIBRARY_PATH) may have unintended consequences, so it's not a good idea to use them in your environment permanently.