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NAME WWW::RobotRules - database of robots.txt-derived permissions SYNOPSIS use WWW::RobotRules; my $rules = WWW::RobotRules->new('MOMspider/1.0'); use LWP::Simple qw(get); { my $url = "http://some.place/robots.txt"; my $robots_txt = get $url; $rules->parse($url, $robots_txt) if defined $robots_txt; } { my $url = "http://some.other.place/robots.txt"; my $robots_txt = get $url; $rules->parse($url, $robots_txt) if defined $robots_txt; } # Now we can check if a URL is valid for those servers # whose "robots.txt" files we've gotten and parsed: if($rules->allowed($url)) { $c = get $url; ... } DESCRIPTION This module parses /robots.txt files as specified in "A Standard for Robot Exclusion", at <http://www.robotstxt.org/wc/norobots.html> Webmasters can use the /robots.txt file to forbid conforming robots from accessing parts of their web site. The parsed files are kept in a WWW::RobotRules object, and this object provides methods to check if access to a given URL is prohibited. The same WWW::RobotRules object can be used for one or more parsed /robots.txt files on any number of hosts. The following methods are provided: $rules = WWW::RobotRules->new($robot_name) This is the constructor for WWW::RobotRules objects. The first argument given to new() is the name of the robot. $rules->parse($robot_txt_url, $content, $fresh_until) The parse() method takes as arguments the URL that was used to retrieve the /robots.txt file, and the contents of the file. $rules->allowed($uri) Returns TRUE if this robot is allowed to retrieve this URL. $rules->agent([$name]) Get/set the agent name. NOTE: Changing the agent name will clear the robots.txt rules and expire times out of the cache. ROBOTS.TXT The format and semantics of the "/robots.txt" file are as follows (this is an edited abstract of <http://www.robotstxt.org/wc/norobots.html>): The file consists of one or more records separated by one or more blank lines. Each record contains lines of the form <field-name>: <value> The field name is case insensitive. Text after the '#' character on a line is ignored during parsing. This is used for comments. The following <field-names> can be used: User-Agent The value of this field is the name of the robot the record is describing access policy for. If more than one *User-Agent* field is present the record describes an identical access policy for more than one robot. At least one field needs to be present per record. If the value is '*', the record describes the default access policy for any robot that has not not matched any of the other records. The *User-Agent* fields must occur before the *Disallow* fields. If a record contains a *User-Agent* field after a *Disallow* field, that constitutes a malformed record. This parser will assume that a blank line should have been placed before that *User-Agent* field, and will break the record into two. All the fields before the *User-Agent* field will constitute a record, and the *User-Agent* field will be the first field in a new record. Disallow The value of this field specifies a partial URL that is not to be visited. This can be a full path, or a partial path; any URL that starts with this value will not be retrieved Unrecognized records are ignored. ROBOTS.TXT EXAMPLES The following example "/robots.txt" file specifies that no robots should visit any URL starting with "/cyberworld/map/" or "/tmp/": User-agent: * Disallow: /cyberworld/map/ # This is an infinite virtual URL space Disallow: /tmp/ # these will soon disappear This example "/robots.txt" file specifies that no robots should visit any URL starting with "/cyberworld/map/", except the robot called "cybermapper": User-agent: * Disallow: /cyberworld/map/ # This is an infinite virtual URL space # Cybermapper knows where to go. User-agent: cybermapper Disallow: This example indicates that no robots should visit this site further: # go away User-agent: * Disallow: / This is an example of a malformed robots.txt file. # robots.txt for ancientcastle.example.com # I've locked myself away. User-agent: * Disallow: / # The castle is your home now, so you can go anywhere you like. User-agent: Belle Disallow: /west-wing/ # except the west wing! # It's good to be the Prince... User-agent: Beast Disallow: This file is missing the required blank lines between records. However, the intention is clear. SEE ALSO LWP::RobotUA, WWW::RobotRules::AnyDBM_File COPYRIGHT Copyright 1995-2009, Gisle Aas Copyright 1995, Martijn Koster This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.