NAME

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

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 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

  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

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.