Re: Less greedy pattern match

"Ed Morton" <morton@[EMAIL PROTECTED]
> wrote in message 
news:4807A618.5020501@[EMAIL PROTECTED]
>
>
> On 4/17/2008 1:32 PM, pk wrote:
>> On Wednesday 16 April 2008 05:23, Ed Morton wrote:
>>
>>
>>>There's no "less greedy" operator (to be honest, I'm not sure what that
>>>really means or why it'd be more useful than a different RE)
>>
>>
>> Well, perl REs have non-greedy match. It can be useful, for example,
when
>> parsing html or xml. The classical example is something like this
(please
>> note that I'm not a perl guru - alas -):
>>
>> $ cat file.html
>> <tag><section><t1>foo</t1><t2>blah</t2><t1>bar
>> </t1></section>
>> <section><t1>baz
>> </t1><t2>blah</t2><t1>baz</t1></section></tag>
>>
>> Suppose you want to remove only what's inside <t1> tags (tags included)

>> and
>> keep everything else, without apriori knowledge of how the lines are
>> formatted.
>>
>> The simple perl one-liner:
>>
>> $ perl -p0e 's%<t1>.+?</t1>%%gs' file.html
>> <tag><section><t2>blah</t2></section>
>> <section><t2>blah</t2></section></tag>
>>
>> does what can't be done with sed. The "+?" is the non-greedy notation
>> for "one or more", just like "*?" is the non-greedy operator for "zero
or
>> more", etc.
>>
>> Note that I'm not saying that that cannot be done using other 
>> methods...that
>> was just an example to demonstrate how non-greedy match can be useful.
>>
>
> Yeah, that is a bit simpler than the awk equivalent:
>
> $ cat file
> <tag><section><t1>foo</t1><t2>blah</t2><t1>bar</t1></section>
> <section><t1>baz</t1><t2>blah</t2><t1>baz</t1></section></tag>
>
> $ awk
'{o="</t1>";n=SUBSEP;gsub(o,n);gsub("<t1>[^"n"]*"n,"");gsub(n,o)}1' 
> file
> <tag><section><t2>blah</t2></section>
> <section><t2>blah</t2></section></tag>
>
> or something else to chop up and reassemble the record. It is a pity
there 
> isn't
> a "not" operator for RE elements other than characters within [...].
>
> Oh well...
>
> Ed.
>

Wouldn't this do?
gawk -v RS='</*t1>' -v ORS=""  'RT!="</t1>"{print}'