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Re: Deleting some regexp/simple expression from lots of files in a secure way

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Bob McGowan <bob_mcgowan@symantec.com> writes:

> On 05/14/2010 10:52 AM, Merciadri Luca wrote:
>> "Boyd Stephen Smith Jr." <bss@iguanasuicide.net> writes:
> ---removed on purpose---
>>> (find $dir -type f -exec sed -i -e "s/$regexp//" {} \;) for all files in a 
>>> directory.
>> Thanks both. (@Andrei: it was in the content of the file, sorry not to
>> have specified it before.)
>> I am using the second command. The problem is that, for one set of
>> files (that I have selected, no problem for this), I have to use a
>> really simple expression: I need to find all the occurences of
>> `\paragraph{}' and replace them with nothing (i.e. with `'). I know
>> regexps, but replacing `$regexp' with `\paragraph{}' gives error
>> messages. Any idea? Thanks.
> In Boyd's example, you can see 'find' uses '{}' as a place holder, to be
> replaced by each file name as it's found.
>>From the 'find' man page:
> -exec command ;
>     Execute  command;  true  if 0 status is returned.  All following
>     arguments to find are taken to be arguments to the command until
>     an  argument  consisting of ‘;’ is encountered.  The string ‘{}’
>     is replaced by the current file name being processed  everywhere
>                                          emphasis added:  ^^^^^^^^^^
>     it occurs in the arguments to the command, not just in arguments
>     where it is alone, as in some versions of find. ...
> So, you get file names in both places.  Since file names are probably
> relative paths, they will contain added slashes, which confuse sed.
> I could not find any reference to how to make '{}' be handled literally
> by find.
> You could try using a '.*' or '.?' between the braces in the sed
> expression and see if that stops find from replacing them.  Since they
> both expand to a 'zero or ...', they will match '{}'.  The problem being
> they will also match the longest '{...}' in the line, so all lines would
> have to have no more than one pair.  As I don't do tex, I don't know if
> this can be counted on or not.
> sed does have a '-r / --regexp-extended' option, and some 'extended'
> regex engines allow specifying a 'shortest' rather than 'longest' match,
> but I don't have any experience with extended regex in sed, you will
> have to experiment.

- -- 
Merciadri Luca
See http://www.student.montefiore.ulg.ac.be/~merciadri/
- -- 

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