How to show shared library dependencies in Linux

Linux programs can share library code. ldd shows the shared libraries a trusted Linux executable resolves and identifies dependencies that are not found.

ldd asks the dynamic loader to trace the shared objects for a trusted ELF executable or shared object. Lines with ⇒ show the required library name and the file selected by the loader, while not found marks a dependency missing from the active search rules. The listing does not enumerate every plugin or library an application loads later through its own logic, such as a call to dlopen.

Use readelf or objdump for binaries from untrusted sources because ldd can run loader-controlled code on some inputs. Direct ELF metadata only shows entries such as NEEDED libraries, while ldd remains the better check for a trusted binary when runtime search paths and transitive dependencies matter.

1. Run ldd on the trusted executable or shared object.

   $ ldd /usr/bin/bash
   	linux-vdso.so.1 (0x0000ffff941dc000)
   	libtinfo.so.6 => /usr/lib/aarch64-linux-gnu/libtinfo.so.6 (0x0000ffff93f90000)
   	libc.so.6 => /usr/lib/aarch64-linux-gnu/libc.so.6 (0x0000ffff93dc0000)
   	/lib/ld-linux-aarch64.so.1 (0x0000ffff94190000)

   The target can be an executable, plugin, or other shared object. A resolved line shows the library name on the left and the selected file path on the right.

   A statically linked executable or a non-ELF file such as a shell script can produce not a dynamic executable instead of a dependency list. This differs from a listed library marked not found. A shell script's interpreter is a separate executable with its own dependencies.

2. Check the output for unresolved libraries.

   $ ldd /opt/report/bin/report-runner
   	linux-vdso.so.1 (0x0000ffffbbe07000)
   	libreportcore.so.3 => not found
   	libc.so.6 => /usr/lib/aarch64-linux-gnu/libc.so.6 (0x0000ffffbbbc0000)
   	/lib/ld-linux-aarch64.so.1 (0x0000ffffbbdc0000)

   Do not copy a random .so file into a system library directory to make this line disappear. The cause may be a missing package, an incomplete application bundle, or an incorrect loader search path for that application.

3. Re-run ldd once the missing dependency is available to the loader.

   $ ldd /opt/report/bin/report-runner
   	linux-vdso.so.1 (0x0000ffff8aaef000)
   	libreportcore.so.3 => /opt/report/lib/libreportcore.so.3 (0x0000ffff8aa40000)
   	libc.so.6 => /usr/lib/aarch64-linux-gnu/libc.so.6 (0x0000ffff8a870000)
   	/lib/ld-linux-aarch64.so.1 (0x0000ffff8aaa0000)

   The absence of not found confirms that the loader can resolve the listed dependencies. Run the program's normal functional test when startup alone does not prove the application works.

4. Read direct ELF dependency entries without invoking the loader.

   $ readelf --dynamic /usr/bin/bash
   
   Dynamic section at offset 0x17f5f8 contains 30 entries:
     Tag        Type                         Name/Value
    0x0000000000000001 (NEEDED)             Shared library: [libtinfo.so.6]
    0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]
    0x0000000000000001 (NEEDED)             Shared library: [ld-linux-aarch64.so.1]
   ##### snipped #####

   readelf --dynamic reads the file metadata. The NEEDED rows are direct dependencies recorded in the binary, not the full runtime dependency tree.

5. Use verbose ldd output when symbol version requirements matter.

   $ ldd --verbose /usr/bin/bash
   	linux-vdso.so.1 (0x0000ffffb46b5000)
   	libtinfo.so.6 => /usr/lib/aarch64-linux-gnu/libtinfo.so.6 (0x0000ffffb4470000)
   	libc.so.6 => /usr/lib/aarch64-linux-gnu/libc.so.6 (0x0000ffffb42a0000)
   	/lib/ld-linux-aarch64.so.1 (0x0000ffffb4670000)
   
   	Version information:
   	/usr/bin/bash:
   		ld-linux-aarch64.so.1 (GLIBC_2.17) => /lib/ld-linux-aarch64.so.1
   		libtinfo.so.6 (NCURSES6_TINFO_5.0.19991023) => /usr/lib/aarch64-linux-gnu/libtinfo.so.6
   		libc.so.6 (GLIBC_2.25) => /usr/lib/aarch64-linux-gnu/libc.so.6
   ##### snipped #####

   Version rows help compare a binary against libraries on another host when a program works on one system but fails after copying, upgrading, or restoring it.