Re: PCRE

[Peter Boughton]

Unless I'm missing messages, the original thread is before I subscribed 
to this list? It is a shame the quote omitted name and date.

Anyhow...

On 02/06/2023 14:59, Sebastian Carlos wrote:
> I want to point out something that may have been missed at first:
>
> Grep's PCRE support (grep -P) does not include the multi-line processing
> features, Therefore I think that shouldn't be an impediment to implement
> PCRE support in sed.
>
> According to Grep manual, 2.4 "grep Programs":
>
> > By default, grep applies each regexp to a line at a time, so the [PCRE]
> ‘(?s)’ directive (making ‘.’ match line breaks) is generally ineffective.

Checking both "man grep" on Debian and the PDF manual I have to hand 
(GNU Grep v3.4), neither of them contain that text. Nor does a quick 
search of the grep source for "generally ineffective" return any results.

One can easily demonstrate that it *is* effective:

$ echo -e 'abc\na\nc' | grep -zoP 'a.c'
abc

$ echo -e 'abc\na\nc' | grep -zoP '(?s)a.c'
abca
c

However, even if it didn't work, it wouldn't really be relevant - with 
or without newline-related features there is no need for PCRE in Sed 
when one can just use Perl.