From: Roman Perepelitsa <roman.perepelitsa@gmail.com>
To: Mikael Magnusson <mikachu@gmail.com>
Cc: Jon Oster <jon.i.oster@gmail.com>, zsh-users@zsh.org
Subject: Re: Bug/regression: tt(RANDOM) seed not updating when $RANDOM is used in a pipe
Date: Sun, 2 Jul 2023 09:29:29 +0200 [thread overview]
Message-ID: <CAN=4vMoOikPvfbzqM3weAsNWnNPTjHW_49q3RuW4Xv_gAgv=zg@mail.gmail.com> (raw)
In-Reply-To: <CAHYJk3ThphEYqo04Y3YjT4T1KgzmrvbQ+xPwTK1iJcjGCcyGfw@mail.gmail.com>
On Sun, Jul 2, 2023 at 9:19 AM Mikael Magnusson <mikachu@gmail.com> wrote:
>
> On 6/28/23, Jon Oster <jon.i.oster@gmail.com> wrote:
> > In 5.8.1, $RANDOM seems not to update its state when the command $RANDOM
> > was used in is piped somewhere. For example:
> >
> > # echo $RANDOM
> > 18163
> > # echo $RANDOM
> > 23472
> > # echo $RANDOM
> > 27685
> > # echo $RANDOM|cat
> > 10178
> > # echo $RANDOM|cat
> > 10178
> > # echo $RANDOM
> > 10178
> > # echo $RANDOM
> > 17862
>
> A simple workaround for this, whether you consider it a bug or a feature,
> % () { echo $1 | cat } $RANDOM
> 21589
> % () { echo $1 | cat } $RANDOM
> 301
>
> or
> % echo $RANDOM > >(cat)
> 1324
> % echo $RANDOM > >(cat)
> 9460
An alternative workaround is to use a random number generator whose
state is kept outside of the current process. Here's an example:
https://gist.github.com/romkatv/a6cede40714ec77d4da73605c5ddb36a. An
added advantage of this approach is that you get a 32-bit number
rather than the 15-bit provided by $RANDOM.
Roman.
prev parent reply other threads:[~2023-07-02 7:30 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-28 20:10 Jon Oster
2023-06-29 2:46 ` Eric Cook
2023-06-29 5:42 ` Bart Schaefer
2023-06-29 14:41 ` Ray Andrews
2023-06-29 14:56 ` Roman Perepelitsa
2023-06-29 17:53 ` Mikael Magnusson
2023-06-29 18:15 ` Roman Perepelitsa
2023-06-29 23:41 ` Bart Schaefer
2023-07-02 7:17 ` Mikael Magnusson
2023-07-02 7:29 ` Roman Perepelitsa [this message]
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