Re: [PATCH] Add example to rand.3

[Jonny Grant <jg@jguk.org>]

Hi Alex

On 26/12/2022 22:29, Alejandro Colomar wrote:
> Hi Jonny,
> 
> On 12/26/22 22:50, Jonny Grant wrote:
>> Hi Alejandro
> 
> Please send also to my email.
> 
>> Please find below a patch.
>>
>> 2022-12-26  Jonathan Grant <jg@jguk.org>
>>     * man3/rand.3: Add example to rand.3 seed with time(NULL)
>>
>>
>>  From 2d4501354ea6c465173fe6c089dfbcc80393a644 Mon Sep 17 00:00:00 2001
>> From: Jonathan Grant <jg@jguk.org>
>> Date: Mon, 26 Dec 2022 21:48:17 +0000
>> Subject: [PATCH] add rand.3 example
>>
>> Signed-off-by: Jonathan Grant <jg@jguk.org>
> 
> time(NULL) is not too good.  If you call it several times per second, you'll find that it only changes the seed every second.  There are better ways to produce a good seed.
> 
> However, I prefer suggesting arc4random() rather than workarounding rand(3) to get good results.
> 
> Florian, did you already merge arc4random() to glibc?

Hopefully arc4random will come soon. Maybe rand.3 could then be updated to SEE ALSO that.

I would only mention to call srand once to seed, but you're right there are lots of other ways to get a seed.
Jonny