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