Tony Abou-Assaleh wrote:
> On Fri, 8 Aug 2008, Francis Litterio wrote:
>
>> The grep/egrep man page says this:
>>
>> Grep understands two different versions of regular expression syntax:
>> "basic" and "extended." In GNU grep, there is no difference in
>> available functionality using either syntax. In other implementa-
>> tions, basic regular expressions are less powerful.
>>
>> But I see this behavior with grep 2.5.1:
>>
>> $ echo foobar | grep 'fo+bar'
>> $ echo foobar | egrep 'fo+bar'
>> foobar
>>
>> So the claim in the man page that "there is no difference in available
>> functionality using either syntax", doesn't seem to be true.
>
> Francis,
>
> The main difference between basic and extended regular expressions in GNU
> grep is that only . and * have a special meaning in basic regular
> expression, all other characters must be escaped before they become
> special.
OK. I think I get it. The man page is saying that while grep and egrep
have the same _functionality_, they use different _syntax_ to achieve
that functionality:
$ echo foobar | grep 'fo\{2\}bar'
foobar
$ echo foobar | egrep 'fo{2}bar'
foobar
Correct?
I would maintain that the man page's phrasing is somewhat confusing.
--
Fran
