Bogus assumption prevents d2u/u2d/conv/etal working on mixed files

Hughes, Bill Bill.Hughes@cox.co.uk
Wed Apr 7 09:05:00 GMT 2004


> Sent: 06 April 2004 16:20  From: Dave Korn
..snip..
> > From: cygwin-owner On Behalf Of Hughes, Bill
> > Sent: 06 April 2004 14:59
> 
> > > Sent: 06 April 2004 14:10  From: fergus@xxxxxxxxxxxxxxxx
> > ..snip..
> > > 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)?
> > I'm no expert but
> > grep [\x00] foo.bar
> > might be what you're after.
> 
> Nope.  That will grep for a lower case x or a zero:
> 
> DKAdmin@ubik /swtools/windows/bin> echo "abcxdef" > test1.txt
> DKAdmin@ubik /swtools/windows/bin> echo "0123456" > test2.txt
> DKAdmin@ubik /swtools/windows/bin> grep [\x61] test?.txt
> test1.txt:abcxdef
> test2.txt:0123456
> DKAdmin@ubik /swtools/windows/bin> grep [\x16] test?.txt
> test1.txt:abcxdef
> test2.txt:0123456
> 
>   grep is not printf, and an escaped shell metacharacter is 
> not the same
> thing as a C-compiler escaped control char sequence in a 
> string literal:
> 
> DKAdmin@ubik /swtools/windows/bin> grep [\r] test?.txt
> DKAdmin@ubik /swtools/windows/bin> grep [\n] test?.txt
> DKAdmin@ubik /swtools/windows/bin> echo >>test1.txt
> DKAdmin@ubik /swtools/windows/bin> grep [\n] test?.txt
> DKAdmin@ubik /swtools/windows/bin> grep [\r] test?.txt
> DKAdmin@ubik /swtools/windows/bin> wc -l test1.txt
>       2 test1.txt
> DKAdmin@ubik /swtools/windows/bin>
Doh, I said I wasn't an expert.
I put it down to two things:
Insufficient testing - my test cases all worked as I expected, so I
obviously didn't have enough of them. I ought to know better by now.
Insufficient knowledge. A little learning being a dangerous thing etc. Mind
you the grep man and info pages (and google come to that) weren't a lot of
help.
Apologies (wipes egg from face).

Bill
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