ldd(1) - man - phpMan

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  lead‐
       ing 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 in‐
       spect  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  informa‐
       tion  by attempting to directly execute the program, which may lead to the execution of what‐
       ever code is defined in the program's ELF interpreter, and perhaps to execution of  the  pro‐
       gram  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  ob‐
              jects 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  5.10 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/.



                                             2019-03-06                                       LDD(1)