14.3. "netrc" — netrc file processing
*************************************

**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 – as determined by "os.path.expanduser()" –
   will be read.  Otherwise, a "FileNotFoundError" exception will be
   raised. 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".

   Changed in version 3.4: Added the POSIX permission check.

   Changed in version 3.7: "os.path.expanduser()" is used to find the
   location of the ".netrc" file when *file* is not passed as
   argument.

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.


14.3.1. 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.

Note: Passwords are limited to a subset of the ASCII character set.
  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.
