Question

I’d like to list the symbols a program loads from a specific library. You can list the needed libraries with ldd:

    ldd -v myExecutable

This gives something like the following output:

    libgcc_s.so.1 (GCC_3.0) => /lib/i386-linux-gnu/libgcc_s.so.1
    libc.so.6 (GLIBC_2.1) => /lib/i386-linux-gnu/libc.so.6
    libc.so.6 (GLIBC_2.11) => /lib/i386-linux-gnu/libc.so.6
    libc.so.6 (GLIBC_2.1.3) => /lib/i386-linux-gnu/libc.so.6
    libc.so.6 (GLIBC_2.0) => /lib/i386-linux-gnu/libc.so.6

Now I’d like to know which symbols are loaded from which library. Specifically, in my case I’d like to find those that are loaded from GLIBC_2.11 and eventually get rid of them.

(I’m already using ligcc to avoid linking against new symbols – now I’d like to see which symbols are not available before 2.11)

Answer 1

nm might satisfy what you’re after. Just used it on my executable, and it does give versions of the library along with the symbol. eg:

U tan@@GLIBC_2.0

so you could do a grep to find only the version you’re interested in.