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Date: Mon, 02 Sep 2019 06:32:27 -0700 (PDT)
From: Steven Penny <svnpenn@gmail.com>
References: <5D6C6749.1080706@tlinx.org>
To: cygwin@cygwin.com
Subject: Re: change in pattern matching in pager /usr/bin/less
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On Sun, 01 Sep 2019 17:50:17, L A Walsh wrote:
> part of this is that the new cygwin less appears to use Obsolete REs
> that don't support '+'.  That may be a compile flag.
> 
> I don't know why \s is not working, however, 'awk' used to be the definitive
> Extended (modern) RE reference and does use \s for whitespace.
> 
> My  linux less is at version 458 (POSIX RegEx)
> my cygwin less is at version 530 (POSIX RegEX)

I have same version as you:

    $ less --version
    less 530 (POSIX regular expressions)

"+" is defined with PCRE, but also under ERE, which is what is used by "awk" and
"grep -E". Its only BRE that doesnt define "+". Not sure why this isnt working
for you but my less uses ERE. Another syntax under ERE is "{1,}", but that wont
help you if your ERE is missing.

In regard to "\s", thats not defined by BRE or ERE, so you would need PCRE for
that. Workaround is to use "[[:blank:]]", "[[:space]]", or simply use the space
character. I havent seen many man pages using tabs. For example doing "man man"
and searching for "[[:cntrl:]]" returns nothing.


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