string(TIMESTAMP output "%d;%H;%I;%j;%m;%M;%S;%U;%w;%y;%Y") message("~${output}~") list(LENGTH output output_length) set(expected_output_length 11) if(NOT output_length EQUAL ${expected_output_length}) message(FATAL_ERROR "expected ${expected_output_length} entries in output " "with all specifiers; found ${output_length}") endif()