# 18.12 `nntplib` -- NNTP protocol client

This module defines the class `NNTP` which implements the client side of the NNTP protocol. It can be used to implement a news reader or poster, or automated news processors. For more information on NNTP (Network News Transfer Protocol), see Internet RFC 977.

Here are two small examples of how it can be used. To list some statistics about a newsgroup and print the subjects of the last 10 articles:

    >>> s = NNTP('news.cwi.nl')
    >>> resp, count, first, last, name = s.group('comp.lang.python')
    >>> print 'Group', name, 'has', count, 'articles, range', first, 'to', last
    Group comp.lang.python has 59 articles, range 3742 to 3803
    >>> resp, subs = s.xhdr('subject', first + '-' + last)
    >>> for id, sub in subs[-10:]: print id, sub
    ...
    3792 Re: Removing elements from a list while iterating...
    3793 Re: Who likes Info files?
    3794 Emacs and doc strings
    3795 a few questions about the Mac implementation
    3796 Re: executable python scripts
    3797 Re: executable python scripts
    3798 Re: a few questions about the Mac implementation
    3799 Re: PROPOSAL: A Generic Python Object Interface for Python C Modules
    3802 Re: executable python scripts
    3803 Re: \POSIX{} wait and SIGCHLD
    >>> s.quit()
    '205 news.cwi.nl closing connection.  Goodbye.'

To post an article from a file (this assumes that the article has valid headers):

    >>> s = NNTP('news.cwi.nl')
    >>> f = open('/tmp/article')
    >>> s.post(f)
    '240 Article posted successfully.'
    >>> s.quit()
    '205 news.cwi.nl closing connection.  Goodbye.'

The module itself defines the following items:

class `NNTP`( | host[, port [, user[, password [, readermode] [, usenetrc]]]])

  Return a new instance of the `NNTP` class, representing a connection to the NNTP server running on host host, listening at port port. The default port is 119. If the optional user and password are provided, or if suitable credentials are present in /.netrc and the optional flag usenetrc is true (the default), the "`AUTHINFO USER`" and "`AUTHINFO PASS`" commands are used to identify and authenticate the user to the server. If the optional flag readermode is true, then a "`mode reader`" command is sent before authentication is performed. Reader mode is sometimes necessary if you are connecting to an NNTP server on the local machine and intend to call reader-specific commands, such as "`group`". If you get unexpected `NNTPPermanentError`s, you might need to set readermode. readermode defaults to `None`. usenetrc defaults to `True`.

  Changed in version 2.4: usenetrc argument added.

exception `NNTPError`
  Derived from the standard exception `Exception`, this is the base class for all exceptions raised by the `nntplib` module.

exception `NNTPReplyError`
  Exception raised when an unexpected reply is received from the server. For backwards compatibility, the exception `error_reply` is equivalent to this class.

exception `NNTPTemporaryError`
  Exception raised when an error code in the range 400-499 is received. For backwards compatibility, the exception `error_temp` is equivalent to this class.

exception `NNTPPermanentError`
  Exception raised when an error code in the range 500-599 is received. For backwards compatibility, the exception `error_perm` is equivalent to this class.

exception `NNTPProtocolError`
  Exception raised when a reply is received from the server that does not begin with a digit in the range 1-5. For backwards compatibility, the exception `error_proto` is equivalent to this class.

exception `NNTPDataError`
  Exception raised when there is some error in the response data. For backwards compatibility, the exception `error_data` is equivalent to this class.