What is DYLD and how to clear the Shared Cache?

UPDATE : JAN.08.2009 : DYLD  is the dynamic link editor:  The error below is an error message from the dyld.  Sometimes, during the dynamic link operation of a compiled the target libraries differ from the linker.  End result, linking can not be accomplished.

The biggest reason why your here is you probably found SuperDuper!  (Awesome Program, pay for the license...  You'll thank me from today until MAC OS IC). Every once in a while when SuperDuper!  restores an image upon reboot you may receive : "dyld: shared cached file was build against a different libSystem.dylib, ignoring cache"  Which typically raises an eyebrow or two. No worries, all this means is during a restore of some sort, in this case SuperDuper! , the cache was built with a different operating system's library (ie: Leopard to Snow Leopard).  

A very specific scenario is when backing up one's Leopard installed Macintosh HD with SuperDuper!  (Will call this backup A). Than installing or upgrading Snow Leopard 10.6.X to the hard drive and creating a backup of the fresh install (Will call this backup B) (Note: This procedure is a VERY smart thing to do, by the way) both systems are now captured from pre and post upgrade of a new operating system.

Now, for some reason one may want to fall back to the Leopard system and uses Backup A with SuperDuper!  to restore the systems Macintosh HD.  During the restore the shared cache is rebuilt by SuperDuper!  before the reboot to the new OS occurs. Now it is at this point or when restoring later back to Backup B that the cache generated does not finish or never gets cleared out correctly for the most current OS.

Once the system is rebooted and one drops to a terminal shell an error maybe seen as shown below: 

 "dyld: shared cached file was build against a different libSystem.dylib, ignoring cache" 

The solution is way less more dramatic than the TERMINAL error above: 

In a terminal shell type in the following command [Solution Here]

$ sudo update_dyld_shared_cache -force

You should receive a similar response below:

update_dyld_shared_cache[4392] current i386 cache file invalid because /System/Library/PrivateFrameworks/DesktopServicesPriv.framework/Versions/A/DesktopServicesPriv has changed

update_dyld_shared_cache: warning mismatched install path in /System/Library/CoreServices/RawCamera.bundle/Contents/MacOS/RawCamera for /usr/lib/libgcc_s.1.dylib

update_dyld_shared_cache: warning mismatched install path in /System/Library/CoreServices/RawCamera.bundle/Contents/Resources/MetadataLib.dylib for /usr/lib/libgcc_s.1.dylib

update_dyld_shared_cache[4392] current x86_64 cache file invalid because /System/Library/PrivateFrameworks/DesktopServicesPriv.framework/Versions/A/DesktopServicesPriv has changed

update_dyld_shared_cache: warning mismatched install path in /System/Library/CoreServices/RawCamera.bundle/Contents/MacOS/RawCamera for /usr/lib/libgcc_s.1.dylib

update_dyld_shared_cache: warning mismatched install path in /System/Library/CoreServices/RawCamera.bundle/Contents/Resources/MetadataLib.dylib for /usr/lib/libgcc_s.1.dylib

Your cache is now updated and your system should been rolling along nicely!

Cheers,

sos 

tags: dyld  cache  superduper  restore  mac  osx  force  

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