Re: grep

[Holger Lehmann]

Am Dienstag, 25. Juni 2002 17:28 schrieb Alfred M. Szmidt:
> * Holger Lehmann writes:
--snipp--
> > I was working on old data. There is an example included in test.txt.
> > This old data sometimes contains an "empty" row with a "backspace" (\b or
> > ^H resp. 0xa0)  at the beginning of the line.
> > I wanted to skip these lines.
> > My initial attempt was to grep for those lines and check the outcome:
> >
> > $ grep '^\b' < test.txt > backspace.txt
>
> From the info manual for grep:
>  The symbol `\b' matches the empty string at the edge of a word.

Ok, ok I admit it: *I am* stupid. I got that from some other manpage where I 
found all the escape chars.

>
> Which is probobly what is happening.  Grepping for an ^H works just
> fine (you can insert it with C-v C-h in bash).  The file `blah'
> contains ^H's.
>
> address@hidden:~$ grep '^^H' blah | wc -c
>       5

Does not work, sorry. I tried that. Try it out and use the test.txt file 
attached to my original message. You might even send me a shell script.
Typing this:

grep '^<Control-V><Control-H>' test.txt

and pressing enter yields zero lines.
Typing this:

grep '^<Control-Q><Control-V><Control-H>' test.txt

and pressing enter yields zero lines as well.
In both cases
grep '^^H' test.txt
appears on the command line.
Using the same quoting in vi and running the script has the same effect.

Now for a different idea: anyone knows if I can grep for a char when I know 
the octal or hexadecimal code for it ? Like 0xa0 or 0240 ??? 
tr does this with \NNN for octal numbers ... I was not able to find any 
equivalent for grep so far ....
(Maybe I am not only stupid but blind as well ?)

- Thanks in advance, Holger


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