13.4. "netrc" — netrc file processing
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1.5.2 新版功能.

**Source code:** Lib/netrc.py

======================================================================

The "netrc" class parses and encapsulates the netrc file format used
by the Unix **ftp** program and other FTP clients.

class netrc.netrc([file])

   A "netrc" instance or subclass instance encapsulates data from  a
   netrc file.  The initialization argument, if present, specifies the
   file to parse.  If no argument is given, the file ".netrc" in the
   user’s home directory will be read.  Parse errors will raise
   "NetrcParseError" with diagnostic information including the file
   name, line number, and terminating token. If no argument is
   specified on a POSIX system, the presence of passwords in the
   ".netrc" file will raise a "NetrcParseError" if the file ownership
   or permissions are insecure (owned by a user other than the user
   running the process, or accessible for read or write by any other
   user). This implements security behavior equivalent to that of ftp
   and other programs that use ".netrc".

   在 2.7.6 版更改: Added the POSIX permissions check.

exception netrc.NetrcParseError

   Exception raised by the "netrc" class when syntactical errors are
   encountered in source text.  Instances of this exception provide
   three interesting attributes:  "msg" is a textual explanation of
   the error, "filename" is the name of the source file, and "lineno"
   gives the line number on which the error was found.


13.4.1. netrc Objects
=====================

A "netrc" instance has the following methods:

netrc.authenticators(host)

   Return a 3-tuple "(login, account, password)" of authenticators for
   *host*. If the netrc file did not contain an entry for the given
   host, return the tuple associated with the ‘default’ entry.  If
   neither matching host nor default entry is available, return
   "None".

netrc.__repr__()

   Dump the class data as a string in the format of a netrc file.
   (This discards comments and may reorder the entries.)

Instances of "netrc" have public instance variables:

netrc.hosts

   Dictionary mapping host names to "(login, account, password)"
   tuples.  The ‘default’ entry, if any, is represented as a pseudo-
   host by that name.

netrc.macros

   Dictionary mapping macro names to string lists.

注解: Passwords are limited to a subset of the ASCII character set.
  Versions of this module prior to 2.3 were extremely limited.
  Starting with 2.3, all ASCII punctuation is allowed in passwords.
  However, note that whitespace and non-printable characters are not
  allowed in passwords.  This is a limitation of the way the .netrc
  file is parsed and may be removed in the future.
