Provided by: libc6_2.9-4ubuntu6_i386 bug

NAME

       ld.so/ld-linux.so - dynamic linker/loader

DESCRIPTION

       ld.so  loads  the  shared  libraries  needed by a program, prepares the
       program to run, and then runs it.  Unless explicitly specified via  the
       -static  option  to  ld  during  compilation,  all  Linux  programs are
       incomplete and require further linking at run time.

       The necessary shared libraries needed by the program are  searched  for
       in the following order

       o      Using      the      environment     variable     LD_LIBRARY_PATH
              (LD_AOUT_LIBRARY_PATH  for  a.out  programs).   Except  if   the
              executable  is  a  setuid/setgid  binary,  in  which  case it is
              ignored.

       o      From the cache file /etc/ld.so.cache which contains  a  compiled
              list  of  candidate  libraries previously found in the augmented
              library path.

       o      In the default path /lib, and then /usr/lib.

COMMAND LINE OPTIONS

       --list List all dependencies and how they are resolved.

       --verify
              Verify that program  is  dynamically  linked  and  this  dynamic
              linker can handle it.

       --library-path PATH
              Override   LD_LIBRARY_PATH  environment  variable  setting  (see
              below).

       --ignore-rpath LIST
              Ignore RPATH and RUNPATH information in object  names  in  LIST.
              This  option  has  been  supported by glibc2 for about one hour.
              Then it was renamed into:

       --inhibit-rpath LIST

ENVIRONMENT

       LD_LIBRARY_PATH
              A colon-separated list of directories in which to search for ELF
              libraries  at  execution-time.   Similar to the PATH environment
              variable.

       LD_PRELOAD
              A whitespace-separated list of additional,  user-specified,  ELF
              shared  libraries  to  be loaded before all others.  This can be
              used  to  selectively  override  functions   in   other   shared
              libraries.   For  setuid/setgid  ELF binaries, only libraries in
              the standard search directories that are  also  setgid  will  be
              loaded.

       LD_TRACE_LOADED_OBJECTS
              If  present,  causes  the  program  to  list its dynamic library
              dependencies, as if run by ldd, instead of running normally.

       LD_BIND_NOW
              If present, causes the dynamic linker to resolve all symbols  at
              program startup instead of when they are first referenced.

       LD_BIND_NOT
              Do  not  update the GOT (global offset table) and PLT (procedure
              linkage table) after resolving a symbol.

       LD_AOUT_LIBRARY_PATH
              A colon-separated list of directories in  which  to  search  for
              a.out   libraries   at  execution-time.   Similar  to  the  PATH
              environment variable.

       LD_AOUT_PRELOAD
              The name of an additional, user-specified, a.out shared  library
              to  be loaded after all others.  This can be used to selectively
              override functions in other shared libraries.

       LD_NOWARN
              Suppress warnings about a.out libraries with incompatible  minor
              version numbers.

       LD_WARN
              If set to non-empty string, warn about unresolved symbols.

       LD_KEEPDIR
              Don’t ignore the directory in the names of a.out libraries to be
              loaded.  Use of this option is strongly discouraged.

       LD_DEBUG
              Output verbose debugging information about the  dynamic  linker.
              If  set to ‘all’ prints all debugging information it has, if set
              to ‘help’ prints a help message about which  categories  can  be
              specified in this environment variable.

       LD_DEBUG_OUTPUT
              File  where  LD_DEBUG  output  should  be  fed  into, default is
              standard output. LD_DEBUG_OUTPUT is  ignored  for  setuid/setgid
              binaries.

       LD_VERBOSE
              If set to non-empty string, output symbol versioning information
              about the program if querying information about the program (ie.
              either  LD_TRACE_LOADED_OBJECTS  has  been  set,  or  --list  or
              --verify options have been given to the dynamic linker).

       LD_PROFILE
              Shared object to be profiled.

       LD_PROFILE_OUTPUT
              File where  LD_PROFILE  output  should  be  stored,  default  is
              standard  output.  LD_DEBUG_OUTPUT  is ignored for setuid/setgid
              binaries.

       LD_ASSUME_KERNEL
              Every DSO (Dynamic Shared Object, aka shared library)  can  tell
              the  dynamic  linker  in  glibc  which minimum OS ABI version is
              needed. The information about the  minimum  OS  ABI  version  is
              encoded  in a ELF note section usually named .note.ABI-tag. This
              is used to determine which library to load when multiple version
              of   the   same   library  is  installed  on  the  system.   The
              LD_ASSUME_KERNEL  environment  variable  overrides  the   kernel
              version used by the dynamic linker to determine which library to
              load.

RPATH TOKEN EXPANSION

       The runtime linker provides a number of tokens that can be used  in  an
       rpath specification (DT_RPATH or DT_RUNPATH).

       $ORIGIN
              ld.so understands the string $ORIGIN (or equivalently ${ORIGIN})
              in an rpath specification to mean the directory  containing  the
              application   executable.   Thus,   an  application  located  in
              somedir/app      could      be      compiled      with       gcc
              -Wl,-rpath,’$ORIGIN/../lib’  so  that  it  finds  an  associated
              shared library in somedir/lib no matter where somedir is located
              in the directory hierarchy.

       $PLATFORM
              The  string  $PLATFORM (or equivalently ${PLATFORM}) in an rpath
              specifcation expands  to  the  processor  type  of  the  current
              machine. Please note that on some architectures the Linux kernel
              doesn’t provide a platform string to the dynamic linker.

       $LIB   The string $LIB (or equivalently ${LIB}) in an rpath corresponds
              to  the system libraries directory, which is /lib for the native
              architecture on FHS compliant GNU/Linux systems.

FILES

       /lib/ld.so          a.out dynamic linker/loader
       /lib/ld-linux.so.*  ELF dynamic linker/loader
       /etc/ld.so.cache    File containing a compiled list of  directories  in
                           which  to  search for libraries and an ordered list
                           of candidate libraries.
       /etc/ld.so.preload  File containing a whitespace separated list of  ELF
                           shared  libraries  to be loaded before the program.
                           libraries  and  an  ordered   list   of   candidate
                           libraries.
       /etc/ld.so.nohwcap  When  this  file is present the dynamic linker will
                           load the non-optimized version of a  library,  even
                           if the CPU supports the optimized version.
       lib*.so*            shared libraries

SEE ALSO

       ldd(1), ldconfig(8).

BUGS

       Currently  ld.so has no means of unloading and searching for compatible
       or newer version of libraries.

       ld.so functionality is only available for  executables  compiled  using
       libc version 4.4.3 or greater.

AUTHORS

       David  Engel,  Eric  Youngdale,  Peter  MacDonald,  Hongjiu  Lu,  Linus
       Torvalds, Lars Wirzenius and Mitch D’Souza  (not  necessarily  in  that
       order).

                                  26 May 2007                         LD.SO(8)