Command not found message

When running invalid commands without any parameters or options, in my experience we get only two kinds of messages which are exemplified below: ~$ Date No command 'Date' found, did you mean: Command 'yate' from package 'yate' (universe) Command 'date' from package 'coreutils' (main) Command 'late' from package 'late' (universe) Command 'kate' from package 'kate' (universe) Date: command not found ~$ fjldjflsk fjldjflsk: command not found ~$ I'm interested in knowing more about how this works. Specifically, when can I know which of these two kinds of messages I'm going to get prior to running the command? Is there some kind of environment variable or any other device that would allow me to alter this behavior easily? I'd like to get only the second kind of message.