This function works like ENGINE_ctrl() with the exception of taking a
command name instead of a command number, and can handle optional commands.
See the comment on ENGINE_ctrl_cmd_string() for an explanation on how to
use the cmd_name and cmd_optional.
This function works like ENGINE_ctrl() with the exception of taking a command name instead of a command number, and can handle optional commands. See the comment on ENGINE_ctrl_cmd_string() for an explanation on how to use the cmd_name and cmd_optional.