August 2012
Intermediate to advanced
609 pages
19h 16m
English
Content preview from Regular Expressions Cookbook, 2nd Edition
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Broken Links Reported in Web Logs
Problem
You have a log for your website in the Combined Log Format. You want to check the log for any errors caused by broken links on your own website.
Solution
"(?:GET|POST)●(?<file>[^#?●"]+)(?:[#?][^●"]*)?●HTTP/[0-9.]+"●404●↵ (?:[0-9]+|-)●"(?<referrer>http://www\.yoursite\.com[^"]*)"
| Regex options: None |
| Regex flavors: .NET, Java 7, XRegExp, PCRE 7, Perl 5.10, Ruby 1.9 |
"(?:GET|POST)●(?P<file>[^#?●"]+)(?:[#?][^●"]*)?●HTTP/[0-9.]+"●404●↵ (?:[0-9]+|-)●"(?P<referrer>http://www\.yoursite\.com[^"]*)"
| Regex options: None |
| Regex flavors: PCRE 4, Perl 5.10, Python |
"(?:GET|POST)●([^#?●"]+)(?:[#?][^●"]*)?●HTTP/[0-9.]+"●404●↵ (?:[0-9]+|-)●"(http://www\.yoursite\.com[^"]*)"
| Regex options: None |
| Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby |
Discussion
When a visitor clicks a link on your website that points to a file on your own site that does not exist, the visitor gets a “page not found” error. Your web server will write an entry in its log that contains the file that does not exist as the requested object, status code 404, and the page that contains the broken link as the referrer. So you need to extract the requested object and the referrer from log entries that have status code 404 and a referring URL on your own website.
One way to do this would be to use your favorite programming
language to write a script that implements Combined Log Format. While iterating over all the
matches, check whether the “status” group captured 404 and whether the “referrer” ...
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I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.