The following descriptions of the options first give the older command-line usage, then the new configfile line. All files except the configfile are checked for changes before each page is fetched, so they can may edited without restarting the proxy. To decide if a pattern matches a target, the domains are compared first, then the paths. To compare the domains, the pattern domain and the target domain specified in the URL are each broken into their components. If all of the pattern components find their match in the target, then the domains are considered a match.
Case is irrelevant when comparing domain components.
A successfully matching pattern can be an anchored substring of a target, but not vice versa. Thus if a pattern doesn't specify a domain, it matches all domains. If a numeric port is specified in the pattern domain, then the target port must match as well. The default port in a target is port 80. If the domain and port match, then the target URL path is checked for a match against the path in the pattern.