hi James,
you are seeing this error message because many Perl regular expression
language flavors do not allow negative lookbehinds which match
variable number of bytes. In your expression, you have a list of
branches where each branch matches a different number of bytes (for
example, "lt" matches just 2 bytes, while "email_opened" matches 12).
In other words, the lookbehind does not match the same number of bytes
in all cases. For the same reason, you would get an error for
(?<!aaa|bb), but not for (?<!aaa|bbb). The regex dialect that is
implemented by pcregrep is not having this restriction.
For the workaround, you could consider reimplementing the same logic
via negative lookahead which can match variable number of bytes. For
example, maybe something like this would help:
^(?!\S+(lt|unsubscribe_get|email_opened)\.php)\S+\.php
Also, you should make sure that lookahead is evaluated at an expected
position in the input string (the above example uses ^ to anchor it to
the beginning of string), otherwise lookahead could produce unexpected
results.
hope this helps,
risto
2017-04-15 0:13 GMT+03:00 James Lay <j...@slave-tothe-box.net>:
> Resending due to large attachment being sent:
>
> Topic :) I THOUGHT I had this right...pcregrep and regex101.com has no
> issues, however I'm seeing the below:
>
> Rule in /etc/sec.conf at line 19: Invalid regular expression
> '(\S+(?<!lt|unsubscribe_get|email_opened)\.php\?id=[A-Z]{1}[A-Z0-9a-z]{4})':
> Variable length lookbehind not implemented in regex
> m/(\S+(?<!lt|unsubscribe_get|email_opened)\.php\?id=[A-Z]{1}[A-Z0-9a-z]{4})/
> at /usr/local/bin/sec line 602, <CONFFILE> line 26.
>
> So hopefully I'm matching on:
>
> \S+(?<!lt|unsubscribe_get|email_opened)\.php\?id=[A-Z]{1}[A-Z0-9a-z]{4}
>
> \S+ - any string
> (?<!lt|unsubscribe_get|email_opened) negative lookbehind saying "don't
> match lt or unsuscribe_get or email_opened in the previous \S+"
> \.php\?id=[A-Z]{1}[A-Z0-9a-z]{4} match .php?="one capital letter""four
> upper or lower case letters or numbers"
>
> Am I missing something glaring? Thank you.
>
> James
>
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