WWW::RobotsRules - Parse robots.txt files
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; ... }
This module parses a robots.txt file as specified in "A Standard for Robot Exclusion", described in <URL: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 WWW server.
The parsed file is kept in the WWW::RobotRules object, and this object provide 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.
The format and semantics of the "/robots.txt" file are as follows (this is an edited abstract of <URL: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
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: /
LWP::RobotUA, WWW::RobotRules::AnyDBM_File
To install LWP, copy and paste the appropriate command in to your terminal.
cpanm
cpanm LWP
CPAN shell
perl -MCPAN -e shell install LWP
For more information on module installation, please visit the detailed CPAN module installation guide.