Linux Applications Debugging Techniques/The dynamic linker

Dependencies ldd -d -r /path/to/binary A script to visualize libraries and their dependencies. Binaries Analysis Tools tldd Resolved symbols To find out which dynamic library is a symbol coming from: $ LD_DEBUG_OUTPUT=sym.log LD_DEBUG=bindings /bin/ls $ cat sym.log.7688 | grep malloc 7688: binding file /lib/i686/cmov/libc.so.6 [0] to /lib/i686/cmov/libc.so.6 [0]: normal symbol `__malloc_initialize_hook' [GLIBC_2.0] 7688: binding file /lib/i686/cmov/libc.so.6 [0] to /bin/ls [0]: normal symbol `malloc' [GLIBC_2.0] 7688: binding file /lib/i686/cmov/libc.so.6 [0] to /lib/i686/cmov/libc.so.6 [0]: normal symbol `__malloc_hook' [GLIBC_2.0] 7688: binding file /lib/ld-linux.so.2 [0] to /lib/i686/cmov/libc.so.6 [0]: normal symbol `malloc' [GLIBC_2.0] 7688: binding file /lib/i686/cmov/libc.so.6 [0] to /lib/i686/cmov/libc.so.6 [0]: normal symbol `malloc' [GLIBC_2.0] 7688: binding file /bin/ls [0] to /lib/i686/cmov/libc.so.6 [0]: normal symbol `malloc' [GLIBC_2.0] $ LD_DEBUG=help /bin/ls Valid options for the LD_DEBUG environment variable are: libs display library search paths reloc display relocation processing files display progress for input file symbols display symbol table processing bindings display information about symbol binding versions display version dependencies all all previous options combined statistics display relocation statistics unused determined unused DSOs help display this help message and exit To direct the debugging output into a file instead of standard output a filename can be specified using the LD_DEBUG_OUTPUT environment variable. References man 8 ld.so libc symbols visibility & linking Notes It is run under whatever credentials would be accorded to the application program; thus, for example, if a set-user-ID-root program is being executed, the dynamic linker will run with an effective user ID of root. Varia A look at dynamic linking