Take a single positive integer as a command-line argument and executes the file called "pi.sh" once for each integer from 1 to N inclusive

1. you must check for valid input (N must be an integer between 2 and 9 inclusive)

2. You must output this usage message to the screen if N is not valid:

" N - number of iterations of pi.sh, must be between 2 and 9 "