bc: Readline and Libedit Options

 
 7 Readline and Libedit Options
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 GNU 'bc' can be compiled (via a configure option) to use the GNU
 'readline' input editor library or the BSD 'libedit' library.  This
 allows the user to do more editing of lines before sending them to 'bc'.
 It also allows for a history of previous lines typed.  When this option
 is selected, 'bc' has one more special variable.  This special variable,
 HISTORY is the number of lines of history retained.  A value of -1 means
 that an unlimited number of history lines are retained.  This is the
 default value.  Setting the value of HISTORY to a positive number
 restricts the number of history lines to the number given.  The value of
 0 disables the history feature.  For more information, read the user
 manuals for the GNU 'readline', 'history' and BSD 'libedit' libraries.
 One can not enable both 'readline' and 'libedit' at the same time.