How to do shell programming

[John <yuancc@pc.jaring.my>]

Mr/Ms
        i want to do a shell program, which is as the user to input some
character, and the final output of the character should be reverse.
example :

input : a b c d e f g h i j
output : j i h g f e d c b a

the user can input as much he/she want

i'm greatefull for you help
thank you