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The libwww-perl collection is a set of Perl modules which provides a simple and consistent application programming interface to the World-Wide Web. The main focus of the library is to provide classes and functions that allow you to write WWW clients. The library also contain modules that are of more general use and even classes that help you imp…
Tag: WWW-RobotRules…

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    WWW::RobotRules - database of robots.txt-derived permissions

     use WWW::RobotRules;
     my $rules = WWW::RobotRules->new('MOMspider/1.0');

     use LWP::Simple qw(get);

       my $url = "";
       my $robots_txt = get $url;
       $rules->parse($url, $robots_txt) if defined $robots_txt;

       my $url = "";
       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;

    This module parses /robots.txt files as specified in "A Standard for
    Robot Exclusion", at <>
    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.

        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.

    The format and semantics of the "/robots.txt" file are as follows (this
    is an edited abstract of <>):

    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 *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.

       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.

    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

      User-agent: *
      Disallow: /cyberworld/map/ # This is an infinite virtual URL space

      # Cybermapper knows where to go.
      User-agent: cybermapper

    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
      # 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

    This file is missing the required blank lines between records. However,
    the intention is clear.

    LWP::RobotUA, WWW::RobotRules::AnyDBM_File

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