Ldd (Unix) Explained

ldd (List Dynamic Dependencies) is a

• nix

utility that prints the shared libraries required by each program or shared library specified on the command line.^[1] It was developed by Roland McGrath and Ulrich Drepper.^[2] If some shared library is missing for any program, that program won't come up.

Security

ldd is a shell script that executes the program given as argument, and shouldn't be used with untrusted binaries. The ldd manual page suggests to use the following command using the objdump and grep utilities as alternative:^[3] user@home ~/ $ objdump -p /path/program | grep NEEDED

Usage examples

user@home ~/ $ ldd /usr/bin/mp3blaster linux-vdso.so.1 => (0x00007fff8fdff000) libsidplay.so.1 => /usr/lib/libsidplay.so.1 (0x00007f4ea98ec000) libvorbisfile.so.3 => /usr/lib/libvorbisfile.so.3 (0x00007f4ea96e4000) libvorbis.so.0 => /usr/lib/libvorbis.so.0 (0x00007f4ea94b6000) libncurses.so.5 => /lib/libncurses.so.5 (0x00007f4ea9273000) libpthread.so.0 => /lib/libpthread.so.0 (0x00007f4ea9056000) libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x00007f4ea8d41000) libm.so.6 => /lib/libm.so.6 (0x00007f4ea8abe000) libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x00007f4ea88a7000) libc.so.6 => /lib/libc.so.6 (0x00007f4ea8523000) libogg.so.0 => /usr/lib/libogg.so.0 (0x00007f4ea831c000) libdl.so.2 => /lib/libdl.so.2 (0x00007f4ea8118000) /lib64/ld-linux-x86-64.so.2 (0x00007f4ea9b59000)user@home ~/ $ ldd /usr/lib/i386-linux-gnu/libstdc++.so.6.0.20 linux-gate.so.1 (0xb7733000) libm.so.6 => /lib/i386-linux-gnu/i686/cmov/libm.so.6 (0xb75da000) libc.so.6 => /lib/i386-linux-gnu/i686/cmov/libc.so.6 (0xb742f000) /lib/ld-linux.so.2 (0xb7734000) libgcc_s.so.1 => /lib/i386-linux-gnu/libgcc_s.so.1 (0xb7411000)

Notes and References

1. Web site: ldd(1) – Linux man page. die.net . December 28, 2011.
2. Web site: ldd Source Code. stuff.mit.edu. March 26, 2014.
3. Web site: ldd(1): print shared library dependencies - Linux man page. 2020-11-18. linux.die.net.