WWW::RobotRules(3)

NAME
WWW::RobotsRules - Parse robots.txt files

SYNOPSIS
 require WWW::RobotRules;
 my $robotsrules = new WWW::RobotRules 'MOMspider/1.0';
 use LWP::Simple qw(get);
 $url = "http://some.place/robots.txt";
 my $robots_txt = get $url;
 $robotsrules->parse($url, $robots_txt);
 $url = "http://some.other.place/robots.txt";
 my $robots_txt = get $url;
 $robotsrules->parse($url, $robots_txt);
 # Now we are able to check if a URL is valid for those servers that
 # we have obtained and parsed "robots.txt" files for.
 if($robotsrules->allowed($url)) {
     $c = get $url;
     ...
 }

DESCRIPTION
This module parses a /robots.txt file as specified in "A Standard for Robot Exclusion", described in <http://info.webcrawler.com/mak/projects/robots/norobots.html> Webmasters can use the /robots.txt file to disallow conforming robots access to parts of their web site.

The parsed file is kept in the WWW::RobotRules object, and this object provides methods to check if access to a given URL is prohibited. The same WWW::RobotRules object can parse multiple /robots.txt files.

The following methods are provided: This is the constructor for WWW::RobotRules objects. The first argument given to new() is the name of the robot. The parse() method takes as arguments the URL that was used to retrieve the /robots.txt file, and the contents of the file. Returns TRUE if this robot is allowed to retrieve this URL. 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://info.webcrawler.com/mak/projects/robots/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: 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 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

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: /

SEE ALSO
the LWP::RobotUA manpage, the WWW::RobotRules::AnyDBM_File manpage