Bash is a POSIX shell (sh(1) compatible) command interpreter.` Many useful features have been added with inspiration drawn from the Korn & C shells.` New and unique extensions are occasionally added to the shell.` There is also support for custom run-time extensions via the enable builtin command.` Bash may be compiled to be POSIX compliant by default as specified by the Shell and Utilities portion of the POSIX specification (IEEE Standard 1003.1).`