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X-Authentication-Warning: slinky.cs.nyu.edu: pechtcha owned process doing -bs
Date: Wed, 16 Jul 2003 16:43:13 -0400 (EDT)
From: Igor Pechtchanski <pechtcha AT cs DOT nyu DOT edu>
Reply-To: cygwin AT cygwin DOT com
To: fergus AT bonhard DOT uklinux DOT net
cc: cygwin AT cygwin DOT com
Subject: Re: Cygwin's vanilla sed : capabilities and limitations
In-Reply-To: <000701c34b9a$1c7e6c80$6fc82486@medschool.dundee.ac.uk>
Message-ID: <Pine.GSO.4.44.0307161635350.21206-100000@slinky.cs.nyu.edu>
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On Wed, 16 Jul 2003 fergus AT bonhard DOT uklinux DOT net wrote:

> This is probably a cheat question (non-central Cygwin issue) but it is about
> Cygwin's vanilla sed.
>
> AND it is only asked in order eventually to provide anybody interested with
> the elegant-est possible script for making a portable Cygwin CD.

Someone already mentioned Perl.  Another tool is "ed".  Both are pretty
heavyweight.  If you want to do it in straight sed, examples are below:

> Q1. Querying info sed reveals the expression matcher to be "greedy",
> matching the longest possible string. Is there a way to make it match the
> shortest possible, so that echo aaabbbccc | sed 's/^.*b//' (altered but
> similar) grabs aaab not aaabbb?

Well, the simplest (off the top of my head) would be 's/^[^b]*b//'.

> Q2. Is there a way using the supplied sed without major enhancements to
> change "abc x def" to "def x abc": that is, to grab two distinct portions
> and swap them (using $1,$2 or \1,\2 or whatever).

Sure.  's/^\(.*\) x \(.*\)$/'.

> Sorry for asking: I know it's a sin: hope the end articulated above
> justifies the means.
>
> Fergus

Hope this helps,
	Igor
-- 
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     |,4-  ) )-,_. ,\ (  `'-'		Igor Pechtchanski, Ph.D.
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