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 file as specified in
``A Standard for Robot Exclusion'', described in
<http://info.webcrawler.com/mak/projects/robots/norobots.html>
Webmasters can use the 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 files.
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 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.
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:
- 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.
- 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
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: /
the LWP::RobotUA manpage, the WWW::RobotRules::AnyDBM_File manpage
