From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 27004 invoked from network); 31 Jan 2002 11:08:14 -0000 Received: from sunsite.dk (130.225.247.90) by ns1.primenet.com.au with SMTP; 31 Jan 2002 11:08:14 -0000 Received: (qmail 19972 invoked by alias); 31 Jan 2002 11:08:03 -0000 Mailing-List: contact zsh-workers-help@sunsite.dk; run by ezmlm Precedence: bulk X-No-Archive: yes X-Seq: 16528 Received: (qmail 19924 invoked from network); 31 Jan 2002 11:07:41 -0000 To: zsh-workers@sunsite.dk (Zsh hackers list) Subject: Re: problems with RANDOM in subshells In-reply-to: "Zefram"'s message of "Thu, 31 Jan 2002 03:46:51 GMT." <20020131034651.GB7382@fysh.org> Date: Thu, 31 Jan 2002 11:07:13 +0000 Message-ID: <14374.1012475233@csr.com> From: Peter Stephenson Zefram wrote: > Clint Adams wrote: > >Should the random-seeding behavior be changed for subshells? > > No. We define $RANDOM to be a PRNG; zshparam(1) speaks of seeding it > (by writing to $RANDOM). Opening a subshell should not interfere with > the PRNG sequence, which one might be relying on to be reproducible. bash has the zsh behaviour, but ksh 88 handles subshells specially. POSIX/SUS doesn't defined RANDOM, but we probably ought to get this specified for David Korn's enhanced shell proposal, given that all three shells under discussion already have RANDOM. It does seem to me that it's unnecessarily hard for a user to take avoiding action in a subshell. At least providing the PID of the subshell process as separate parameter might give them the start, e.g. make $ZSH_REALPID map directly to getpid() --- obviously not with a very high degree of randomness, but I don't think that was a problem in this case. (The advantage over providing a real `random' number is that it takes a minute to write instead of a day.) -- Peter Stephenson Software Engineer CSR Ltd., Science Park, Milton Road, Cambridge, CB4 0WH, UK Tel: +44 (0)1223 392070 ********************************************************************** The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computer. **********************************************************************