[dvdkhlng]

SED is shorter (0 byte). SED /is/ a turing complete language [1] so don't try to claim that I'm cheating.

  sed < input > output 

:)

[1] http://robertkotcher.com/sed.html

[update] s/set/sed/

[acqq]

The command line equivalent, with Perl:

    perl -pe '' <input >output

[Alphasite_]

Even java can do that setOut(system.in); (iirc)

[dvdkhlng]

> Even java can do that setOut(system.in);

I was referring to an empty SED-program that would then be run via 'sed -f empty-file.sed'. Of course you need >0 bytes to invoke the SED program.