Determine direct shared object dependencies of a Linux binary

Question

How can I easily find out the direct shared object dependencies of a Linux binary in ELF format   I m aware of the ldd tool  but that appears to output all dependencies of a binary  including the dependencies of any shared objects that binary is dependent on

User · Answer

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

User · Answer

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

User · Answer

ldd -v prints the dependency tree under  Version information   section  The first block in that section are the direct dependencies of the binary   See Hierarchical ldd 1

User · Answer

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

[linux] Determine direct shared object dependencies of a Linux binary?

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