:Linux Journal: Modifying a Dynamic Library Without Changing the Source Code
Linux Journal: Modifying a Dynamic Library Without Changing the Source Code Nov 4, 2004, 07 :00 UTC (0 Talkback[s]) (9182 reads) (Other stories by Greg Kroah-Hartman)
"Sometimes, you might want to determine what is happening in a shared library without modifying the library (have you tried to build glibc lately?). Other times, you might want to override only a few functions within a library and get them to do something else--force a process to a specific CPU, prevent a specific USB message from being sent and so on. All of these tasks are possible if you use the LD_PRELOAD environment variable and a small shim program placed between the application and the library.
"As an example, say you create a shared library object called shim.so and want it to be loaded before any other shared library. Say you also want to run the program 'test...'"
