UNIX for Dummies Questions & Answers

I want to generate a random number between 1 and 22.

I believe that the variable $RANDOM generates numbers in the inverval 1-32767.

How do I generate a random integer within a specific interval?

Code:

$(($RANDOM % 22 + 1))

The rules for $RANDOM are in the "man" page for your Shell.
It's usually 0-32767 (not 1-32767).

One idea.
Add 22 to $RANDOM.
Divide by 22 and take the remainder. Add one to that result.
Final result should be in the range 1-22 .

The method for the mathematics in Shell depends on which Shell you are using. Modern Posix Shells include easy ways to divide and return the remainder.


Just read "purdeym" post, which is using Posix Shell arithmetic. Just needs to add 22 to $RANDOM to allow for values of $RANDOM which are less than 22.

I think that code works perfectly...

Code:

>echo $((0 % 22 + 1))
1
>echo $((1 % 22 + 1))
2
>echo $((2 % 22 + 1))
3
>echo $((3 % 22 + 1))
4
>echo $((4 % 22 + 1))
5
>echo $((5 % 22 + 1))
6
>echo $((21 % 22 + 1))
22

>echo $((22 % 22 + 1))
1
>echo $((23 % 22 + 1))
2
>echo $((24 % 22 + 1))
3

But if not, let me know.

So do I.

So do I . Albeit a bit after the fact.