pcWRT support for complex RegEx

[Casino]

pcWRT supports RegEx formatted like this:

~^(www\.)?amazon\.[a-z]{2,}(\.[a-z]{2,})?$

My goal is to block only the main domains while leaving subdomains unblocked. For example, I want to block “amazon.com” but not “aws.amazon.com”, “music.amazon.com”, etc.

Currently, I am using this RegEx:

~^www.amazon.\.*

I was wondering, firstly, if the complex RegEx mentioned at the start of this discussion is supported by pcWRT, and secondly, if this other one:

~^(www\.)?amazon\.

is the most comprehensive option—both in terms of clean syntax and efficiency (i.e., without placing too heavy a load on the router’s hardware).

[support]

First of all, ^ matches the beginning of the string. ~^www.amazon.com will match www.amazon.com but not 1www.amazon.com or a.www.amazon.com. Remember on pcWRT router, the dot without a leading \ matches the dot itself (unlike the standard regex, which matches any single character).

^(www.)?amazon.com matches both www.amazon.com and amazon.com (i.e., the grouping with a question mark matches the group 0 or 1 times).

~^www.amazon.\.* matches anything starting with www.amazon., e.g., www.amazon.com, www.amazon.us, www.amazon.eu etc.

~^(www\.)?amazon\.: the \ preceding the dot changes the meaning of the dot to match any single character. So this regex will match amazon.com, amazon-with-anything-else-here, because there is no end of string anchor $. Apparently, you want the dot to be a literal match here. Thus the correct regex should be: ~^(www.)?amazon., which would match amazon.anything-here, www.amazon.anything-here. But it would not match www.amazonaws.com, because a dot must follow amazon, not an a (in aws).

[Casino]

Could you please tell me if pcWRT supports the first, complex RegEx I wrote at the beginning of my post?

Here is the issue I’m facing: I want to block only the main Amazon domains (such as amazon.it, amazon.com, amazon.es) while leaving all their subdomains unblocked.

I am currently using this RegEx:

~^www.amazon.\.*

but this also seems like a valid alternative:

~^(www\.)?amazon\..*$

Could you recommend the most suitable RegEx for this purpose?

[support]

~^(www.)?amazon. will block all domains starting with amazon., including amazon.it, amazon.com, amazon.es, plus www.amazon.*. But it will not block other subdomains besides www.

[Casino]

I asked some specific questions that haven’t been answered, but never mind. Could you give me a practical example of what this RegEx blocks and doesn’t block?

~^www.amazon.\.*

And what this other one blocks and doesn’t block?

~^(www\.)?amazon\..*$

That way, I’ll be able to understand the practical difference and apply it to other domains. Thanks.

[support]

You can ask AI (e.g., Google) and get a good explanation, with a prompt like this:

The following is a POSIX regex. The only exception is . is a literal dot, but \. is a meta-character that matches a single character. What does it match: ^www.amazon.\.*

[Casino]

I asked you here precisely because AI always returns wrong solutions.

[Author]

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