ldd

LDD(1)                      Linux Programmer's Manual                     LDD(1)



NAME
       ldd - print shared object dependencies

SYNOPSIS
       ldd [option]... file...

DESCRIPTION
       ldd prints the shared objects (shared libraries) required by each program
       or shared object specified on the command line.  An example of its use
       and output (using sed(1) to trim leading white space for readability in
       this page) is the following:

           $ ldd /bin/ls | sed 's/^ */    /'
               linux-vdso.so.1 (0x00007ffcc3563000)
               libselinux.so.1 => /lib64/libselinux.so.1 (0x00007f87e5459000)
               libcap.so.2 => /lib64/libcap.so.2 (0x00007f87e5254000)
               libc.so.6 => /lib64/libc.so.6 (0x00007f87e4e92000)
               libpcre.so.1 => /lib64/libpcre.so.1 (0x00007f87e4c22000)
               libdl.so.2 => /lib64/libdl.so.2 (0x00007f87e4a1e000)
               /lib64/ld-linux-x86-64.so.2 (0x00005574bf12e000)
               libattr.so.1 => /lib64/libattr.so.1 (0x00007f87e4817000)
               libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f87e45fa000)

       In the usual case, ldd invokes the standard dynamic linker (see ld.so(8))
       with the LD_TRACE_LOADED_OBJECTS environment variable set to 1.  This
       causes the dynamic linker to inspect the program's dynamic dependencies,
       and find (according to the rules described in ld.so(8)) and load the
       objects that satisfy those dependencies.  For each dependency, ldd
       displays the location of the matching object and the (hexadecimal)
       address at which it is loaded.  (The linux-vdso and ld-linux shared
       dependencies are special; see vdso(7) and ld.so(8).)

   Security
       Be aware that in some circumstances (e.g., where the program specifies an
       ELF interpreter other than ld-linux.so), some versions of ldd may attempt
       to obtain the dependency information by attempting to directly execute
       the program, which may lead to the execution of whatever code is defined
       in the program's ELF interpreter, and perhaps to execution of the program
       itself.  (In glibc versions before 2.27, the upstream ldd implementation
       did this for example, although most distributions provided a modified
       version that did not.)

       Thus, you should never employ ldd on an untrusted executable, since this
       may result in the execution of arbitrary code.  A safer alternative when
       dealing with untrusted executables is:

           $ objdump -p /path/to/program | grep NEEDED

       Note, however, that this alternative shows only the direct dependencies
       of the executable, while ldd shows the entire dependency tree of the
       executable.

OPTIONS
       --version
              Print the version number of ldd.

       -v, --verbose
              Print all information, including, for example, symbol versioning
              information.

       -u, --unused
              Print unused direct dependencies.  (Since glibc 2.3.4.)

       -d, --data-relocs
              Perform relocations and report any missing objects (ELF only).

       -r, --function-relocs
              Perform relocations for both data objects and functions, and
              report any missing objects or functions (ELF only).

       --help Usage information.

BUGS
       ldd does not work on a.out shared libraries.

       ldd does not work with some extremely old a.out programs which were built
       before ldd support was added to the compiler releases.  If you use ldd on
       one of these programs, the program will attempt to run with argc = 0 and
       the results will be unpredictable.

SEE ALSO
       pldd(1), sprof(1), ld.so(8), ldconfig(8)

COLOPHON
       This page is part of release 5.12 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.



                                   2021-03-22                             LDD(1)