From: Zoltan Hidvegi <hzoli@cs.elte.hu>
To: zsh-workers@math.gatech.edu (Zsh hacking and development)
Subject: Redirection bug
Date: Tue, 4 Jun 1996 00:45:18 +0200 (MET DST) [thread overview]
Message-ID: <199606032245.AAA00255@hzoli.ppp.cs.elte.hu> (raw)
There is a feature which appeared after Zefram's redirection fixes:
% (echo bug >&2) >& /dev/tty >& /dev/null ; sleep 1
bug
bug
sleep 1 is not necessary above, but without sleep 1 the prompt comes back
while the tee process is still running which makes the output less
readable (that's really an other much older bug).
The problem above is the duplicated `bug'. Considering that >& foo is the
> same as foo 2>&1, this produce the same output:
% (echo bug >&2) > /dev/tty 2>&1 > /dev/null 2>&1 ; sleep 1
bug
bug
Or swapping stderr and stdout:
% echo bug 2> /dev/tty >&2 > /dev/null >&2 ; sleep 1
bug
bug
And if we omit > /dev/null:
% echo bug 2> /dev/tty >&2 >&2 ; sleep 1
bug
bug
At this point this behavour seems to be correct. bug is duplicated since
stdout is redirected twice. Here bug was printed only once before
zsh-2.6-beta18. That was probably a bug. But now it is quite
counter-intuitive that >& /dev/tty >& /dev/null duplicates stderr on
/dev/tty. I do not understand redirection staff in exec.c very much but I
do hope that Zefram knows some elegant solution to this problem.
Zoltan
next reply other threads:[~1996-06-04 0:25 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
1996-06-03 22:45 Zoltan Hidvegi [this message]
1996-06-05 14:17 ` Zefram
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