My first thought when I saw that trivial programming question was to write it in Brainfuck.

My second thought was to come here to the comments to see how long it would be before the attempts started.

My third thought was, if you're allowed to use any language at all, I'd go for code golf. Not sure it's possible to do it in fewer characters than:

    #!/bin/sh
    cat

#!/bin/cat -

Clever. You win one internet.