Rev is a Unix command, common on AIX but rare on other Unix flavors, which is highly useful.
.lufesu ylhgih si hcihw ,srovalf xinU rehto no erar tub XIA no nommoc dnammoc xinU a si veR

It takes the input file (stdin, if not specified), and reverses each line of text from beginning to end.
.dne ot gninnigeb morf txet fo enil hcae sesrever dna ,)deificeps ton fi nidts( elif tupni eht sekat tI

This command has no switches.
.sehctiws on sah dnammoc sihT

Perhaps someone's idea of encryption?
?noitpyrcne fo aedi s'enoemos spahreP