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Date:      Wed, 10 Mar 1999 06:29:42 +1000
From:      Greg Black <gjb@comkey.com.au>
To:        cjclark@home.com
Cc:        gjb@comkey.com.au (Greg Black), freebsd-questions@FreeBSD.ORG
Subject:   Re: sh Tutorial 
Message-ID:  <19990309202942.14534.qmail@alpha.comkey.com.au>
In-Reply-To: <199903091540.KAA00613@cc942873-a.ewndsr1.nj.home.com>  of Tue, 09 Mar 1999 10:40:35 EST
References:  <199903091540.KAA00613@cc942873-a.ewndsr1.nj.home.com> 

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> > > Anyone out there know of a good tutorial for the Bourne shell (sh)? In
> > > particular, one with a focus on file descriptors. The few I find and
> > > the manpage say that the following line opens 'temp' for reading and
> > > writing and associates fd 3 with it,
> > > 
> > > exec 3<> temp
> > > 
> > > However, I get,
> > > 
> > > ./fdtest: 3: Syntax error: redirection unexpected
> > > 
> > > Whenever I use a '<>' redirect. What am I doing wrong? If I do either
> > > a '>' or '<' it works.
> > 
> > Seems like /bin/sh has a bug.  It works fine with bash -- and
> > bash comes with a decent man page and substantial additional
> > documentation which is worth reading.
> 
> Found the PR for it, bin/7325. It was reported for 2.2.6 in July of
> last year. For some reason, the PR-sender listed is as 'non-critical'
> and of 'low' priority. IMHO, the potential to break a sh-script that
> should work according to the docs is a bit more severe than that. 

You could try to persuade the maintainers that it matters.  It
may be that people consider it low priority because they don't
use this feature -- I have to say that, in about a million years
of writing shell scripts, I've never even wanted to use the <>
redirection facility ...

In the meantime, if you do need <>, you can use bash.  (I didn't
take the time to see that it *works* in bash, but at least bash
doesn't regard it as a syntax error the way sh does.)

-- 
Greg Black <gjb@acm.org>



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