'''bash''' is one of the common [Unix shells], just like for example '''sh''', [ksh], '''csh''' and others.

The name is an acronym for ''Bourne-Again SHell'', which is a slight pun on the old Bourne shell '''sh'''.

See http://www.gnu.org/software/bash/ for more details.
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There seems to be no [Tcl Heritage] of '''bash''' (at least not yet).