Options Specifying Options Options are primarily referred to by name. These names are case insensitive and underscores are ignored. This inversion can only be done once, so nonobeep is not a synonym for beep .
Some options also have one or more single letter names.
The single letter options can be used on the shell command line, or with the set , setopt and unsetopt builtins, as normal Unix options preceded by - . Some of the single letter option names refer to an option being off, in which case the inversion of that name refers to the option being on. All parameters subsequently defined are automatically exported. If set, these functions try to return to the last prompt if given no numeric argument. If a completion with the cursor in the word was started and it results in only one match, the cursor is placed at the end of the word.