Karl Berry Olaf Bachmann and many others. Conventional libraries, or static libraries, are linked into a program image. This means that each program which uses a static library includes some or all of the library in the program binary on disk. Shared libraries, on the other hand, are a separate file.
Many programs can use a single shared library.
Using a shared library reduces disk space requirements. Since the system can generally share a single executable instance of the shared library among many programs, it also reduces swap space requirements at run time. Another advantage is that it is possible to fix a bug by updating the single shared library file on disk, without requiring all the programs which use the library to be rebuilt. The idea was rapidly adopted by other Unix vendors, appearing in SunOS, HP-UX, AIX, and Digital Unix among others. Unfortunately, each implementation differed in the creation and use of shared libraries and in the specific features which were supported.