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System Libraries

Note that some specialty libraries at the BSD level are not packaged as frameworks. Instead, Mac OS X includes many dynamic libraries in the /usr/lib directory and its subdirectories. Dynamic shared libraries are identified by their .dylib extension. Header files for the libraries are located in /usr/include.

Mac OS X uses symbolic links to point to the most current version of most libraries. When linking to a dynamic shared library, use the symbolic link instead of a link to a specific version of the library. Library versions may change in future versions of Mac OS X. If your software is linked to a specific version, that version might not always be available on the user’s system.

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