Well, that’s probably because the example shown include “reserved” characters used also by the shell you use to run these commands.
But as these characters are different from one shell to another, I can’t give as many examples as there are existing shells.
Keep in mind that these special characters have to be “escaped” when invoking the command from a terminal. Also of course, all commands involving an argument such as image.jpg must replace this filename by a valid image name.