# sort 404s by frequency
awk '($9 ~ /404/)' mylogfilename | awk '{print $9,$7}' | sort | uniq -c | sort -r

takes a url as a keyword and returns the google cache

give a URL and a spider will read the html code and check for the broken links... splits links in two categories, internal, from the same host, and external, outgoing link to different domains. When finished, you will see a report showing all the bad links found, not only 404 status.

Welcome to the world of the Error 404 page.