The following is not one that I wrote, but it is the first example of a complex regular expression that I ever encountered - so I always remember it. It can be found in the procmailrc(5) manpage.
(^(Mailing-List:|Precedence:.*(junk|bulk|list)|To: Multiple recipient
+s of
|(((Resent-)?(From|Sender)|X-Envelope-From):|>?From )([^>]*[^(.
+%@a-z0-9])?(Post(ma?(st(e?r)?|n)|office)|(send)?Mail(er)?|daemon|m(md
+f|ajordomo)|n?uucp
|LIST(SERV|proc)|NETSERV|o(wner|ps)|r(e(quest|sponse)|oot)|b(ou
+nce|bs\.smtp)|echo|mirror|s(erv(ices?|er)|mtp(error)?|ystem)|A(dmin(i
+strator)?|MMGR
|utoanswer))(([^).!:a-z0-9][-_a-z0-9]*)?[%@>\t ][^<)]*(\(.*\).*
+)?)?$([^>]|$)))
I've never tried to dissect it, but looking at it now (and having a somewhat better understanding of regular expressions than I did when I first saw it) I guess it's really not all that complex at all - mainly just lots of alternation.
Cheers,
Darren :)
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.
|