[Q] A mystery (at least for me ...)

[Q] A mystery (at least for me ...)

[Didier Verna]

	HI!

I have something weird in zsh 3.0.5:

verna(pts/6) 143 % hostname
metheny
verna(pts/6) 144 % if echo toto | grep tata ; then echo SUCCESS ; fi      
zsh: done       echo toto | 
zsh: exit 1     grep tata
verna(pts/6) 145 % if echo toto | grep `hostname` ; then echo SUCCESS ; fi  
SUCCESS
verna(pts/6) 146 % if (echo toto | grep `hostname`) ; then echo SUCCESS ; fi
zsh: exit 1     ( echo toto | grep `hostname` )


	Is it a known bug in this version,or am I missing something ? 

Thanks
-- 
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Re: [1997] [Q] A mystery (at least for me ...)

[Danek Duvall]

On Fri, Dec 18, 1998 at 09:44:54AM +0100, Didier Verna wrote:

> verna(pts/6) 145 % if echo toto | grep `hostname` ; then echo SUCCESS ; fi  
> SUCCESS
> 
> 	Is it a known bug in this version,or am I missing something ? 

The following commands might explain ...

if echo toto | grep x`false`; then echo SUCCESS; fi

if echo toto | grep x`true`; then echo SUCCESS; fi


The return value of expression "echo toto | grep `cmd`" is the return value
of cmd, not of grep.

I'm not sure how clearly this is documented in the manpage.  At this point,
I've gotten used to the fact that processes act weirdly around pipes, and
I've learned to work around it.

However, documentation on exactly what is expected might be nice.  I
couldn't find it in the section on process substitution or in the section
on pipelines.  Is it somewhere else?

Danek

Re: [1997] [Q] A mystery (at least for me ...)

[Peter Stephenson]

Danek Duvall wrote:
> On Fri, Dec 18, 1998 at 09:44:54AM +0100, Didier Verna wrote:
> 
> > verna(pts/6) 145 % if echo toto | grep `hostname` ; then echo SUCCESS ; fi 
>  
> > SUCCESS
> > 
> > 	Is it a known bug in this version,or am I missing something ? 
> 
> The return value of expression "echo toto | grep `cmd`" is the return value
> of cmd, not of grep.

[I haven't seen the message this is a reply to here, which is why I'm
replying to this one.]

This is a bug, it's fixed in 3.1.5.  There is a short patch in
zsh-workers message 4397, which you can get from
http://www.zsh.org/mla/ , and which should apply to most versions of
3.x.  You can see the message in
http://www.zsh.org/mla/workers//1998/msg00730.html but you may want to
find a non-html form if you want to apply it automatically.

-- 
Peter Stephenson <pws@ibmth.df.unipi.it>       Tel: +39 050 844536
WWW:  http://www.ifh.de/~pws/
Dipartimento di Fisica, Via Buonarroti 2, 56127 Pisa, Italy

Re: [Q] A mystery (at least for me ...)

[Bart Schaefer]

On Dec 18,  9:44am, Didier Verna wrote:
} Subject: [Q] A mystery (at least for me ...)
}
} verna(pts/6) 145 % if echo toto | grep `hostname` ; then echo SUCCESS ; fi  
} SUCCESS
} 
} 	Is it a known bug in this version,or am I missing something ? 

It's a known bug; patch is in zsh-workers article number 4397 (I believe).

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com