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:mod:`urllib.robotparser` --- Parser for robots.txt
====================================================
.. module:: urllib.robotparser
:synopsis: Load a robots.txt file and answer questions about
fetchability of other URLs.
.. sectionauthor:: Skip Montanaro <skip@pobox.com>
**Source code:** :source:`Lib/urllib/robotparser.py`
.. index::
single: WWW
single: World Wide Web
single: URL
single: robots.txt
--------------
This module provides a single class, :class:`RobotFileParser`, which answers
questions about whether or not a particular user agent can fetch a URL on the
Web site that published the :file:`robots.txt` file. For more details on the
structure of :file:`robots.txt` files, see http://www.robotstxt.org/orig.html.
.. class:: RobotFileParser(url='')
This class provides methods to read, parse and answer questions about the
:file:`robots.txt` file at *url*.
.. method:: set_url(url)
Sets the URL referring to a :file:`robots.txt` file.
.. method:: read()
Reads the :file:`robots.txt` URL and feeds it to the parser.
.. method:: parse(lines)
Parses the lines argument.
.. method:: can_fetch(useragent, url)
Returns ``True`` if the *useragent* is allowed to fetch the *url*
according to the rules contained in the parsed :file:`robots.txt`
file.
.. method:: mtime()
Returns the time the ``robots.txt`` file was last fetched. This is
useful for long-running web spiders that need to check for new
``robots.txt`` files periodically.
.. method:: modified()
Sets the time the ``robots.txt`` file was last fetched to the current
time.
.. method:: crawl_delay(useragent)
Returns the value of the ``Crawl-delay`` parameter from ``robots.txt``
for the *useragent* in question. If there is no such parameter or it
doesn't apply to the *useragent* specified or the ``robots.txt`` entry
for this parameter has invalid syntax, return ``None``.
.. versionadded:: 3.6
.. method:: request_rate(useragent)
Returns the contents of the ``Request-rate`` parameter from
``robots.txt`` as a :term:`named tuple` ``RequestRate(requests, seconds)``.
If there is no such parameter or it doesn't apply to the *useragent*
specified or the ``robots.txt`` entry for this parameter has invalid
syntax, return ``None``.
.. versionadded:: 3.6
The following example demonstrates basic use of the :class:`RobotFileParser`
class::
>>> import urllib.robotparser
>>> rp = urllib.robotparser.RobotFileParser()
>>> rp.set_url("http://www.musi-cal.com/robots.txt")
>>> rp.read()
>>> rrate = rp.request_rate("*")
>>> rrate.requests
3
>>> rrate.seconds
20
>>> rp.crawl_delay("*")
6
>>> rp.can_fetch("*", "http://www.musi-cal.com/cgi-bin/search?city=San+Francisco")
False
>>> rp.can_fetch("*", "http://www.musi-cal.com/")
True
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