DYLD(1) DYLD(1)

NAME
       dyld - the dynamic link editor

SYNOPSIS
       DYLDFRAMEWORKPATH
       DYLDFALLBACKFRAMEWORKPATH
       DYLDLIBRARYPATH
       DYLDFALLBACKLIBRARYPATH
       DYLDROOTPATH
       DYLDSHAREDREGION
       DYLDINSERTLIBRARIES
       DYLDFORCEFLATNAMESPACE
       DYLDIMAGESUFFIX
       DYLDPRINTOPTS
       DYLDPRINTENV
       DYLDPRINTLIBRARIES
       DYLDPRINTLIBRARIESPOSTLAUNCH
       DYLDBINDATLAUNCH
       DYLDNOFIXPREBINDING
       DYLDDISABLEDOFS
       DYLDPRINTAPIS
       DYLDPRINTBINDINGS
       DYLDPRINTINITIALIZERS
       DYLDPRINTREBASINGS
       DYLDPRINTSEGMENTS
       DYLDPRINTSTATISTICS
       DYLDPRINTDOFS

DESCRIPTION
       The  dynamic  linker  uses  the  following environment variables.  They
       affect any program that uses the dynamic linker.

       DDYYLLDDFFRRAAMMEEWWOORRKKPPAATTHH
              This is a colon  separated  list  of  directories  that  contain
              frameworks.   The  dynamic  linker  searches  these  directories
              before it searches for the framework by its  install  name.   It
              allows  you  to  test  new  versions  of existing frameworks. (A
              framework is a library  install  name  that  ends  in  the  form
              XXX.framework/Versions/YYY/XXX  or  XXX.framework/XXX, where XXX
              and YYY are any name.)

              For each framework that a program uses, the dynamic linker looks
              for  the  framework  in each directory in DYLDFRAMEWORKPATH in
              turn. If it looks in all the  directories  and  can't  find  the
              framework,  it  searches the directories in DYLDLIBRARYPATH in
              turn. If it still can't find the  framework,  it  then  searches
              DYLDFALLBACKFRAMEWORKPATH  and  DYLDFALLBACKLIBRARYPATH in
              turn.

              Use the -LL option to otool(1).  to discover the  frameworks  and
              shared libraries that the executable is linked against.

       DDYYLLDDFFAALLLLBBAACCKKFFRRAAMMEEWWOORRKKPPAATTHH
              This  is  a  colon  separated  list  of directories that contain
              frameworks.  It is used as the default location  for  frameworks
              not found in their install path.

              By    default,    it   is   set   to   /Library/Frameworks:/Net-
              work/Library/Frameworks:/System/Library/Frameworks

       DDYYLLDDLLIIBBRRAARRYYPPAATTHH
              This is a colon  separated  list  of  directories  that  contain
              libraries.  The dynamic linker searches these directories before
              it searches the default locations for libraries. It  allows  you
              to test new versions of existing libraries.

              For  each  library that a program uses, the dynamic linker looks
              for it in each directory in DYLDLIBRARYPATH  in  turn.  If  it
              still  can't  find  the  library,  it  then  searches DYLDFALL-
              BACKFRAMEWORKPATH and DYLDFALLBACKLIBRARYPATH in turn.

              Use the -LL option to otool(1).  to discover the  frameworks  and
              shared libraries that the executable is linked against.

       DDYYLLDDFFAALLLLBBAACCKKLLIIBBRRAARRYYPPAATTHH
              This  is  a  colon  separated  list  of directories that contain
              libraries.  It is used as the default location for libraries not
              found  in  their  install  path.   By  default,  it  is  set  to
              $(HOME)/lib:/usr/local/lib:/lib:/usr/lib.

       DDYYLLDDRROOOOTTPPAATTHH
              This is a colon separated  list  of  directories.   The  dynamic
              linker  will prepend each of this directory paths to every image
              access until a file is found.

       DDYYLLDDSSHHAARREEDDRREEGGIIOONN
              This can be "use" (the default), "avoid", or  "private".   Sett-
              ting  it to "avoid" tells dyld to not use the shared cache.  All
              OS dylibs are loaded dynamically just like  every  other  dylib.
              Setting  it  to "private" tells dyld to remove the shared region
              from the process address space and mmap() back in a private copy
              of  the  dyld  shared  cache in the shared region address range.
              This is only useful if the shared cache on disk has been updated
              and is different than the shared cache in use.

       DDYYLLDDIINNSSEERRTTLLIIBBRRAARRIIEESS
              This  is  a  colon  separated  list of dynamic libraries to load
              before the ones specified in the program.  This  lets  you  test
              new  modules  of existing dynamic shared libraries that are used
              in flat-namespace images by loading a temporary  dynamic  shared
              library with just the new modules.  Note that this has no effect
              on images built a two-level namespace  images  using  a  dynamic
              shared library unless DYLDFORCEFLATNAMESPACE is also used.

       DYLDFORCEFLATNAMESPACE
              Force  all  images in the program to be linked as flat-namespace
              images and ignore any two-level namespace  bindings.   This  may
              cause programs to fail to execute with a multiply defined symbol
              error if two-level namespace images are used to allow the images
              to have multiply defined symbols.

       DDYYLLDDIIMMAAGGEESSUUFFFFIIXX
              This  is  set  to a string of a suffix to try to be used for all
              shared libraries used by the program.  For libraries  ending  in
              ".dylib"  the  suffix  is applied just before the ".dylib".  For
              all other libraries the suffix is appended to the library  name.
              This  is  useful  for using conventional "profile" and "debug"
              libraries and frameworks.

       DDYYLLDDPPRRIINNTTOOPPTTSS
              When this is set, the dynamic linker writes to file descriptor 2
              (normally standard error) the command line options.

       DDYYLLDDPPRRIINNTTEENNVV
              When this is set, the dynamic linker writes to file descriptor 2
              (normally standard error) the environment variables.

       DDYYLLDDPPRRIINNTTLLIIBBRRAARRIIEESS
              When this is set, the dynamic linker writes to file descriptor 2
              (normally  standard  error)  the  filenames of the libraries the
              program is using.  This is useful to make sure that the  use  of
              DYLDLIBRARYPATH is getting what you want.

       DDYYLLDDPPRRIINNTTLLIIBBRRAARRIIEESSPPOOSSTTLLAAUUNNCCHH
              This  does  the  same  as  DYLDPRINTLIBRARIES but the printing
              starts after the program gets to its entry point.

       DDYYLLDDBBIINNDDAATTLLAAUUNNCCHH
              When this is set, the dynamic linker binds all undefined symbols
              the program needs at launch time. This includes function symbols
              that can are normally lazily bound at the time  of  their  first
              call.

       DDYYLLDDPPRRIINNTTSSTTAATTIISSTTIICCSS
              Right  before  the  process's  main() is called, dyld prints out
              information about how dyld spent its time.  Useful for analyzing
              launch performance.

       DDYYLLDDNNOOFFIIXXPPRREEBBIINNDDIINNGG
              Normally, dyld will trigger the dyld shared cache to be regener-
              ated if it notices the cache is out of date  while  launching  a
              process.   If  this  environment  variable is set, dyld will not
              trigger a cache rebuild.  This is useful to set while installing
              a large set of OS dylibs, to ensure the cache is not regenerated
              until the install is complete.

       DDYYLLDDDDIISSAABBLLEEDDOOFFSS
              Causes dyld not register dtrace static probes with the kernel.

       DDYYLLDDPPRRIINNTTIINNIITTIIAALLIIZZEERRSS
              Causes dyld to print out a line when running  each  initializers
              in  every image.  Initializers run by dyld included constructors
              for C++ statically  allocated  objects,  functions  marked  with
              attribute((constructor)), and -init functions.

       DDYYLLDDPPRRIINNTTAAPPIISS
              Causes  dyld to print a line whenever a dyld API is called (e.g.
              NSAddImage()).

       DDYYLLDDPPRRIINNTTSSEEGGMMEENNTTSS
              Causes dyld to print out a line containing the name and  address
              range  of  each  mach-o  segment that dyld maps.  In addition it
              prints information about if the image was from the  dyld  shared
              cache.

       DDYYLLDDPPRRIINNTTBBIINNDDIINNGGSS
              Causes  dyld to print a line each time a symbolic name is bound.

       DDYYLLDDPPRRIINNTTDDOOFFSS
              Causes dyld to print out information about dtrace static  probes
              registered with the kernel.


SEE ALSO
       libtool(1), ld(1), otool(1)



Apple Inc.                      March 23, 2007                         DYLD(1)