Editing Shared library (section)

== Formats ==
Many modern operating systems now use a unified format for their shared libraries and executable files. For example:

* [[Microsoft Windows]] uses the [[Portable Executable|Portable Executable (PE)]] format for [[.dll]] files;
* operating systems such as [[Oracle Solaris|Solaris]] and other [[System V Release 4]]-based systems, [[Linux]], and the free-software [[BSD]] operating systems use the [[Executable and Linkable Format]] (ELF) for [[.so file|.so]] files;
* [[Apple Inc.|Apple's]] [[Darwin (operating system)|Darwin]]-based operating systems, such as [[macOS]] and [[iOS]], use the [[Mach-O]] format for [[.dylib]] files.

This offers two main advantages: first, it requires only one loader (building and maintaining a single loader is considered well worth any added complexity). Secondly, it allows an executable file to be used as a shared library (if it has a [[symbol table]]).{{Citation Needed|date=April 2022}}

In some older environments such as [[16-bit Windows]] or [[HP Multi-Programming Executive|MPE]] for the [[HP 3000]], significant restrictions were placed on shared library code, such as only allowing stack-based (local) data.{{Citation Needed|date=April 2022}}