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Re: [Help-bash] How random is $RANDOM?

From: Andreas Kusalananda Kähäri
Subject: Re: [Help-bash] How random is $RANDOM?
Date: Thu, 9 May 2019 14:17:01 +0200
User-agent: Mutt/1.11.4 (2019-03-13)

On Thu, May 09, 2019 at 06:33:07AM -0500, Peng Yu wrote:
> Let's say two bash processes call $RANDOM at the exact same time. Will
> the results be the same? Or the results will be different.

The random number generator used in bash is seeded using a number that
contains the PID of the current shell (as well as the current time).

> Also, is the low bits of $RANDOM more random or the high bits of
> $RANDOM more random. I see examples using $RANDOM%n to map the random
> number to a smaller range. But my understanding in other random
> numbers is that the high bits are more random and using the modulus is
> discouraged. I am not sure what is the recommended usage of $RANDOM to
> map it to a smaller range. Does anybody know the best use of $RANDOM
> in this case? Thanks.

The random number generator itself is short and has a reference to the
relevant paper describing it.

> -- 
> Regards,
> Peng


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