Requirements

To use the readline functions, you need to install
libreadline. You can find libreadline on the home page of the GNU
Readline project, at » http://cnswww.cns.cwru.edu/~chet/readline/rltop.html.
It’s maintained by Chet Ramey, who’s also the author of Bash.

You can also use these functions with the libedit
library, a non-GPL replacement for the readline library. The
libedit library is BSD licensed and available for download from
» http://www.thrysoee.dk/editline/.