Bash - Hex to String -

in bash, how can convert hex-encoded string this:

2e2f65202d6b2022616622 

or

\x2e\x2f\x65\x20\x2d\x6b\x20\x22\x61\x66\x22 

(or similiar) to:

./e -k "af" 

... , execute it?

thanks!

eval `printf "\x2e\x2f\x65\x20\x2d\x6b\x20\x22\x61\x66\x22"`