[bash script] Typed Variables

A '-' turns the option on, while '+' turns it off.

Table 6-1. Declare options

Option	Meaning
-a	The variables are treated as arrays
-f	Use function names only
-F	Display function names without definitions
-i	The variables are treated as integers
-r	Makes the variables read-only ,cann't be unset
-x	Marks the variables for export via the environment