ormaaj_ 1373018337 learn [Difficulty: 7/10]. Write a simple command in Bash that includes the PE: «${_+$(echo moo >&2)}». It must expand the alternate, i.e. _ must be unset.
ormaaj 1373197637 forget
ormaaj 1373197639 learn [Difficulty: 7/10]. Write a simple command in Bash that includes the PE: «${_-$(echo moo >&2)}». It must expand the alternate, i.e. _ must be unset.
ormaaj 1376279593 forget