What Is Bash?
Bash is the shell, or command language interpreter, for the GNU operating system. The name is an acronym for the ‘ Bourne-Again SHell ’, a pun on Stephen Bourne, the author of the direct ancestor of the current Unix shell sh , which appeared in the Seventh Edition Bell Labs Research version of Unix. Bash is largely compatible with sh and incorporates useful features from the Korn shell ksh and the C shell csh . It is intended to be a conformant implementation of the IEEE POSIX Shell and Tools portion of the IEEE POSIX specification ( IEEE Standard 1003.1). It offers functional improvements over sh for both interactive and programming use. While the GNU operating system provides other shells, including a version of csh , Bash is the default shell. Like other GNU software, Bash is quite portable. It currently runs on nearly every version of Unix and a few other operating systems - independently-supported ports exist for MS-DOS , OS/2 , and Windows platforms.