bash: What is Bash?

1 
1 1.1 What is Bash?
1 =================
1 
1 Bash is the shell, or command language interpreter, for the GNU
1 operating system.  The name is an acronym for the 'Bourne-Again SHell',
1 a pun on Stephen Bourne, the author of the direct ancestor of the
1 current Unix shell 'sh', which appeared in the Seventh Edition Bell Labs
1 Research version of Unix.
1 
1    Bash is largely compatible with 'sh' and incorporates useful features
1 from the Korn shell 'ksh' and the C shell 'csh'.  It is intended to be a
1 conformant implementation of the IEEE POSIX Shell and Tools portion of
1 the IEEE POSIX specification (IEEE Standard 1003.1).  It offers
1 functional improvements over 'sh' for both interactive and programming
1 use.
1 
1    While the GNU operating system provides other shells, including a
1 version of 'csh', Bash is the default shell.  Like other GNU software,
1 Bash is quite portable.  It currently runs on nearly every version of
1 Unix and a few other operating systems - independently-supported ports
1 exist for MS-DOS, OS/2, and Windows platforms.
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