ksh does not get enough love it deserves as it is the living ancestor of both, bash and zsh, shells that have inherited, improved upon and extended many feature

ksh does not get enough love it deserves as it is the living ancestor of both, bash and zsh, shells that have inherited, improved upon and extended many features. It has also been a life saver on proprietory UNIX platforms where the default sh was usually the plain sh, with ksh always being available and having the command line editing available («set -o emacs» or «set -o vi») and GNU readline being unavailable. The POSIX shell is effectively ksh.