Determine direct shared object dependencies of a Linux binary?

You can use readelf to explore the ELF headers. readelf -d will list the direct dependencies as NEEDED sections.

 $ readelf -d elfbinDynamic section at offset 0xe30 contains 22 entries:  Tag        Type                         Name/Value 0x0000000000000001 (NEEDED)             Shared library: [libssl.so.1.0.0] 0x0000000000000001 (NEEDED)             Shared library: [libc.so.6] 0x000000000000000c (INIT)               0x400520 0x000000000000000d (FINI)               0x400758 ...

If you want to find dependencies recursively (including dependencies of dependencies, dependencies of dependencies of dependencies and so on)…

You may use ldd command.ldd - print shared library dependencies

The objdump tool can tell you this information. If you invoke objdump with the -x option, to get it to output all headers then you'll find the shared object dependencies right at the start in the "Dynamic Section".

For example running objdump -x /usr/lib/libXpm.so.4 on my system gives the following information in the "Dynamic Section":

Dynamic Section:  NEEDED               libX11.so.6  NEEDED               libc.so.6  SONAME               libXpm.so.4  INIT                 0x0000000000002450  FINI                 0x000000000000e0e8  GNU_HASH             0x00000000000001f0  STRTAB               0x00000000000011a8  SYMTAB               0x0000000000000470  STRSZ                0x0000000000000813  SYMENT               0x0000000000000018  PLTGOT               0x000000000020ffe8  PLTRELSZ             0x00000000000005e8  PLTREL               0x0000000000000007  JMPREL               0x0000000000001e68  RELA                 0x0000000000001b38  RELASZ               0x0000000000000330  RELAENT              0x0000000000000018  VERNEED              0x0000000000001ad8  VERNEEDNUM           0x0000000000000001  VERSYM               0x00000000000019bc  RELACOUNT            0x000000000000001b

The direct shared object dependencies are listing as 'NEEDED' values. So in the example above, libXpm.so.4 on my system just needs libX11.so.6 and libc.so.6.

It's important to note that this doesn't mean that all the symbols needed by the binary being passed to objdump will be present in the libraries, but it does at least show what libraries the loader will try to load when loading the binary.