GENWiki

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 pro-
     gram or shared object specified on the command line.  An example of its
     use and output is the following:

       $ ldd /bin/ls
               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 depen-
     dency, ldd displays the location of the matching object and the  (hexa-
     decimal)  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  alterna-
     tive 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

1. -version

Print the version number of ldd.

1. v, –verbose

Print all information, including, for example, symbol versioning

            information.

1. u, –unused

Print unused direct dependencies. (Since glibc 2.3.4.)

1. d, –data-relocs

Perform relocations and report any missing objects (ELF only).

1. r, –function-relocs

Perform relocations for both data objects and functions, and

            report any missing objects or functions (ELF only).

1. -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 4.16 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/.

                                2017-09-15                            LDD(1)