Hi

The grep command in FreeBSD doesn't support the -P perl compatible switch.

In linux, grep -P is supported.

How can I do this in freebsd via perl? Thx

What search engine terms did you use that didn't answer that question?

Putting "grep perl equivalent" into a search engine gives a number of results, including highlighting the built-in grep function.

try find, install from FreeBSD repo pcregrep or its newer, pcre2grep

1 members found this post helpful.

You can use regular Perl as a direct replacement for grep. Just follow perl's expressive syntax to do the same thing:
See "man perlre" and "man perlrun". That's just one example with Perl, there's more than one way to to it. However, if you are processing HTML or even well-formed XML, then regex is the wrong tool for the job, regardless of language.

You'll survive much better with a proper XML or HTML parser. There are several for Python and Perl or standalone ones like xmlstarlet:

It might seem a little complex at first, but it uses XPath like you would with some of the Python and Perl based XML / HTML parsers, and which are similar to what you have used in CSS already.

grep -P means: Interpret PATTERNS as Perl-compatible regular expressions (PCREs).
That means perl by default will know and recognize those patterns. So I don't really understand this question.
Additionally perl has a function named grep.