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X-Authentication-Warning: slinky.cs.nyu.edu: pechtcha owned process doing -bs
Date: Tue, 6 Apr 2004 15:19:46 -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: Bogus assumption prevents d2u/u2d/conv/etal working on mixed files
Message-ID: <Pine.GSO.4.56.0404061458130.7366@slinky.cs.nyu.edu>
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On Tue, 6 Apr 2004, fergus wrote:

> >> GNU grep detects binary files by looking for a '\0' byte.
>
> I know this is not strictly Cygwin-specific but it _is_ generated by the
> preceding relevant recent comment in a busy thread:
>
> Please can you tell me how to grep for an ASCII 00 (and for that matter
> anything from ASCII 1B to 1F, and 7F to FF)?
>
> (Or, I suppose in general for any of 00-FF though there's a "^A - ^Z" chunk
> at the beginning and a alphanumeric chunk in the middle, that are easily
> found by direct means.)
>
> Fergus

For anything but '\0', grep has no problem matching binary characters, so
you can use something like
	grep -a "`echo -ne "\01"`"
or
	grep -a "^V^A" (from the command line)
to match lines with ^A in them.  Unfortunately, grep uses '\0' as a string
terminator, so the above trick won't work with '\0'.  The best you can
hope to do with grep (or, for that matter, sed) is use "[[:cntrl:]]".

You *can*, however, use perl for this:
	perl -ne 'print if /\0/'

HTH,
	Igor
-- 
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