1WWW::RobotRules(3)    User Contributed Perl Documentation   WWW::RobotRules(3)
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NAME

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

9        use WWW::RobotRules;
10        my $rules = WWW::RobotRules->new('MOMspider/1.0');
11
12        use LWP::Simple qw(get);
13
14        {
15          my $url = "http://some.place/robots.txt";
16          my $robots_txt = get $url;
17          $rules->parse($url, $robots_txt) if defined $robots_txt;
18        }
19
20        {
21          my $url = "http://some.other.place/robots.txt";
22          my $robots_txt = get $url;
23          $rules->parse($url, $robots_txt) if defined $robots_txt;
24        }
25
26        # Now we can check if a URL is valid for those servers
27        # whose "robots.txt" files we've gotten and parsed:
28        if($rules->allowed($url)) {
29            $c = get $url;
30            ...
31        }
32

DESCRIPTION

34       This module parses /robots.txt files as specified in "A Standard for
35       Robot Exclusion", at <http://www.robotstxt.org/wc/norobots.html>
36       Webmasters can use the /robots.txt file to forbid conforming robots
37       from accessing parts of their web site.
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39       The parsed files are kept in a WWW::RobotRules object, and this object
40       provides methods to check if access to a given URL is prohibited.  The
41       same WWW::RobotRules object can be used for one or more parsed
42       /robots.txt files on any number of hosts.
43
44       The following methods are provided:
45
46       $rules = WWW::RobotRules->new($robot_name)
47           This is the constructor for WWW::RobotRules objects.  The first
48           argument given to new() is the name of the robot.
49
50       $rules->parse($robot_txt_url, $content, $fresh_until)
51           The parse() method takes as arguments the URL that was used to
52           retrieve the /robots.txt file, and the contents of the file.
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54       $rules->allowed($uri)
55           Returns TRUE if this robot is allowed to retrieve this URL.
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57       $rules->agent([$name])
58           Get/set the agent name. NOTE: Changing the agent name will clear
59           the robots.txt rules and expire times out of the cache.
60

ROBOTS.TXT

62       The format and semantics of the "/robots.txt" file are as follows (this
63       is an edited abstract of <http://www.robotstxt.org/wc/norobots.html>):
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65       The file consists of one or more records separated by one or more blank
66       lines. Each record contains lines of the form
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68         <field-name>: <value>
69
70       The field name is case insensitive.  Text after the '#' character on a
71       line is ignored during parsing.  This is used for comments.  The
72       following <field-names> can be used:
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74       User-Agent
75          The value of this field is the name of the robot the record is
76          describing access policy for.  If more than one User-Agent field is
77          present the record describes an identical access policy for more
78          than one robot. At least one field needs to be present per record.
79          If the value is '*', the record describes the default access policy
80          for any robot that has not not matched any of the other records.
81
82          The User-Agent fields must occur before the Disallow fields.  If a
83          record contains a User-Agent field after a Disallow field, that
84          constitutes a malformed record.  This parser will assume that a
85          blank line should have been placed before that User-Agent field, and
86          will break the record into two.  All the fields before the User-
87          Agent field will constitute a record, and the User-Agent field will
88          be the first field in a new record.
89
90       Disallow
91          The value of this field specifies a partial URL that is not to be
92          visited. This can be a full path, or a partial path; any URL that
93          starts with this value will not be retrieved
94
95       Unrecognized records are ignored.
96

ROBOTS.TXT EXAMPLES

98       The following example "/robots.txt" file specifies that no robots
99       should visit any URL starting with "/cyberworld/map/" or "/tmp/":
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101         User-agent: *
102         Disallow: /cyberworld/map/ # This is an infinite virtual URL space
103         Disallow: /tmp/ # these will soon disappear
104
105       This example "/robots.txt" file specifies that no robots should visit
106       any URL starting with "/cyberworld/map/", except the robot called
107       "cybermapper":
108
109         User-agent: *
110         Disallow: /cyberworld/map/ # This is an infinite virtual URL space
111
112         # Cybermapper knows where to go.
113         User-agent: cybermapper
114         Disallow:
115
116       This example indicates that no robots should visit this site further:
117
118         # go away
119         User-agent: *
120         Disallow: /
121
122       This is an example of a malformed robots.txt file.
123
124         # robots.txt for ancientcastle.example.com
125         # I've locked myself away.
126         User-agent: *
127         Disallow: /
128         # The castle is your home now, so you can go anywhere you like.
129         User-agent: Belle
130         Disallow: /west-wing/ # except the west wing!
131         # It's good to be the Prince...
132         User-agent: Beast
133         Disallow:
134
135       This file is missing the required blank lines between records.
136       However, the intention is clear.
137

SEE ALSO

139       LWP::RobotUA, WWW::RobotRules::AnyDBM_File
140

142         Copyright 1995-2009, Gisle Aas
143         Copyright 1995, Martijn Koster
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145       This library is free software; you can redistribute it and/or modify it
146       under the same terms as Perl itself.
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150perl v5.16.3                      2012-02-18                WWW::RobotRules(3)
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