help-bash
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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


From: Peng Yu
Subject: Re: [Help-bash] How random is $RANDOM?
Date: Thu, 9 May 2019 07:29:51 -0500

Why only 16 bits $RANDOM is supported? Is there a problem to set 32
bits as the default?

On 5/9/19, Andreas Kusalananda Kähäri <address@hidden> wrote:
> 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).
>
> https://git.savannah.gnu.org/cgit/bash.git/tree/variables.c#n1369
>
>
>>
>> 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.
>
> https://git.savannah.gnu.org/cgit/bash.git/tree/variables.c#n1329
>
>
>>
>> --
>> Regards,
>> Peng
>
> --
> Kusalananda
> Sweden
>


-- 
Regards,
Peng



reply via email to

[Prev in Thread] Current Thread [Next in Thread]