Compare two byte arrays

Ah, now I understand. So, a "char" in your case is supposed to be a std_logic_vector with 8 bits, right?

But then, "commands" should be an array of array of std_logic_vector(7 downto 0). You're missing one level of arrays. You try to initialize a std_logic_vector(7 downto 0) with "x"73746F700000", where "73746F700000" is 48 bits. I wonder why the compiler doesn't complain, but you have to fix that first.