
``ftplib`` --- FTP protocol client
**********************************

This module defines the class ``FTP`` and a few related items. The
``FTP`` class implements the client side of the FTP protocol.  You can
use this to write Python programs that perform a variety of automated
FTP jobs, such as mirroring other ftp servers.  It is also used by the
module ``urllib.request`` to handle URLs that use FTP.  For more
information on FTP (File Transfer Protocol), see Internet **RFC 959**.

Here's a sample session using the ``ftplib`` module:

   >>> from ftplib import FTP
   >>> ftp = FTP('ftp.cwi.nl')   # connect to host, default port
   >>> ftp.login()               # user anonymous, passwd anonymous@
   >>> ftp.retrlines('LIST')     # list directory contents
   total 24418
   drwxrwsr-x   5 ftp-usr  pdmaint     1536 Mar 20 09:48 .
   dr-xr-srwt 105 ftp-usr  pdmaint     1536 Mar 21 14:32 ..
   -rw-r--r--   1 ftp-usr  pdmaint     5305 Mar 20 09:48 INDEX
    .
    .
    .
   >>> ftp.retrbinary('RETR README', open('README', 'wb').write)
   '226 Transfer complete.'
   >>> ftp.quit()

The module defines the following items:

class class ftplib.FTP(host='', user='', passwd='', acct=''[, timeout])

   Return a new instance of the ``FTP`` class.  When *host* is given,
   the method call ``connect(host)`` is made.  When *user* is given,
   additionally the method call ``login(user, passwd, acct)`` is made
   (where *passwd* and *acct* default to the empty string when not
   given).  The optional *timeout* parameter specifies a timeout in
   seconds for blocking operations like the connection attempt (if is
   not specified, the global default timeout setting will be used).

exception exception ftplib.error_reply

   Exception raised when an unexpected reply is received from the
   server.

exception exception ftplib.error_temp

   Exception raised when an error code signifying a temporary error
   (response codes in the range 400--499) is received.

exception exception ftplib.error_perm

   Exception raised when an error code signifying a permanent error
   (response codes in the range 500--599) is received.

exception exception ftplib.error_proto

   Exception raised when a reply is received from the server that does
   not fit the response specifications of the File Transfer Protocol,
   i.e. begin with a digit in the range 1--5.

ftplib.all_errors

   The set of all exceptions (as a tuple) that methods of ``FTP``
   instances may raise as a result of problems with the FTP connection
   (as opposed to programming errors made by the caller).  This set
   includes the four exceptions listed above as well as
   ``socket.error`` and ``IOError``.

See also:

   Module ``netrc``
      Parser for the ``.netrc`` file format.  The file ``.netrc`` is
      typically used by FTP clients to load user authentication
      information before prompting the user.

   The file ``Tools/scripts/ftpmirror.py`` in the Python source
   distribution is a script that can mirror FTP sites, or portions
   thereof, using the ``ftplib`` module. It can be used as an extended
   example that applies this module.


FTP Objects
===========

Several methods are available in two flavors: one for handling text
files and another for binary files.  These are named for the command
which is used followed by ``lines`` for the text version or ``binary``
for the binary version.

``FTP`` instances have the following methods:

FTP.set_debuglevel(level)

   Set the instance's debugging level.  This controls the amount of
   debugging output printed.  The default, ``0``, produces no
   debugging output.  A value of ``1`` produces a moderate amount of
   debugging output, generally a single line per request.  A value of
   ``2`` or higher produces the maximum amount of debugging output,
   logging each line sent and received on the control connection.

FTP.connect(host='', port=0[, timeout])

   Connect to the given host and port.  The default port number is
   ``21``, as specified by the FTP protocol specification.  It is
   rarely needed to specify a different port number.  This function
   should be called only once for each instance; it should not be
   called at all if a host was given when the instance was created.
   All other methods can only be used after a connection has been
   made.

   The optional *timeout* parameter specifies a timeout in seconds for
   the connection attempt. If no *timeout* is passed, the global
   default timeout setting will be used.

FTP.getwelcome()

   Return the welcome message sent by the server in reply to the
   initial connection.  (This message sometimes contains disclaimers
   or help information that may be relevant to the user.)

FTP.login(user='anonymous', passwd='', acct='')

   Log in as the given *user*.  The *passwd* and *acct* parameters are
   optional and default to the empty string.  If no *user* is
   specified, it defaults to ``'anonymous'``.  If *user* is
   ``'anonymous'``, the default *passwd* is ``'anonymous@'``.  This
   function should be called only once for each instance, after a
   connection has been established; it should not be called at all if
   a host and user were given when the instance was created.  Most FTP
   commands are only allowed after the client has logged in.  The
   *acct* parameter supplies "accounting information"; few systems
   implement this.

FTP.abort()

   Abort a file transfer that is in progress.  Using this does not
   always work, but it's worth a try.

FTP.sendcmd(cmd)

   Send a simple command string to the server and return the response
   string.

FTP.voidcmd(cmd)

   Send a simple command string to the server and handle the response.
   Return nothing if a response code corresponding to success (codes
   in the range 200--299) is received.  Raise ``error_reply``
   otherwise.

FTP.retrbinary(cmd, callback, blocksize=8192, rest=None)

   Retrieve a file in binary transfer mode.  *cmd* should be an
   appropriate ``RETR`` command: ``'RETR filename'``. The *callback*
   function is called for each block of data received, with a single
   string argument giving the data block. The optional *blocksize*
   argument specifies the maximum chunk size to read on the low-level
   socket object created to do the actual transfer (which will also be
   the largest size of the data blocks passed to *callback*).  A
   reasonable default is chosen. *rest* means the same thing as in the
   ``transfercmd()`` method.

FTP.retrlines(cmd, callback=None)

   Retrieve a file or directory listing in ASCII transfer mode.  *cmd*
   should be an appropriate ``RETR`` command (see ``retrbinary()``) or
   a command such as ``LIST``, ``NLST`` or ``MLSD`` (usually just the
   string ``'LIST'``). ``LIST`` retrieves a list of files and
   information about those files. ``NLST`` retrieves a list of file
   names.  On some servers, ``MLSD`` retrieves a machine readable list
   of files and information about those files.  The *callback*
   function is called for each line with a string argument containing
   the line with the trailing CRLF stripped.  The default *callback*
   prints the line to ``sys.stdout``.

FTP.set_pasv(boolean)

   Enable "passive" mode if *boolean* is true, other disable passive
   mode. Passive mode is on by default.

FTP.storbinary(cmd, file, blocksize=8192, callback=None)

   Store a file in binary transfer mode.  *cmd* should be an
   appropriate ``STOR`` command: ``"STOR filename"``. *file* is an
   open *file object* which is read until EOF using its ``read()``
   method in blocks of size *blocksize* to provide the data to be
   stored.  The *blocksize* argument defaults to 8192.  *callback* is
   an optional single parameter callable that is called on each block
   of data after it is sent.

FTP.storlines(cmd, file, callback=None)

   Store a file in ASCII transfer mode.  *cmd* should be an
   appropriate ``STOR`` command (see ``storbinary()``).  Lines are
   read until EOF from the open *file object* *file* using its
   ``readline()`` method to provide the data to be stored.  *callback*
   is an optional single parameter callable that is called on each
   line after it is sent.

FTP.transfercmd(cmd, rest=None)

   Initiate a transfer over the data connection.  If the transfer is
   active, send a ``EPRT`` or  ``PORT`` command and the transfer
   command specified by *cmd*, and accept the connection.  If the
   server is passive, send a ``EPSV`` or ``PASV`` command, connect to
   it, and start the transfer command.  Either way, return the socket
   for the connection.

   If optional *rest* is given, a ``REST`` command is sent to the
   server, passing *rest* as an argument.  *rest* is usually a byte
   offset into the requested file, telling the server to restart
   sending the file's bytes at the requested offset, skipping over the
   initial bytes.  Note however that RFC 959 requires only that *rest*
   be a string containing characters in the printable range from ASCII
   code 33 to ASCII code 126.  The ``transfercmd()`` method,
   therefore, converts *rest* to a string, but no check is performed
   on the string's contents.  If the server does not recognize the
   ``REST`` command, an ``error_reply`` exception will be raised.  If
   this happens, simply call ``transfercmd()`` without a *rest*
   argument.

FTP.ntransfercmd(cmd, rest=None)

   Like ``transfercmd()``, but returns a tuple of the data connection
   and the expected size of the data.  If the expected size could not
   be computed, ``None`` will be returned as the expected size.  *cmd*
   and *rest* means the same thing as in ``transfercmd()``.

FTP.nlst(argument[, ...])

   Return a list of file names as returned by the ``NLST`` command.
   The optional *argument* is a directory to list (default is the
   current server directory).  Multiple arguments can be used to pass
   non-standard options to the ``NLST`` command.

FTP.dir(argument[, ...])

   Produce a directory listing as returned by the ``LIST`` command,
   printing it to standard output.  The optional *argument* is a
   directory to list (default is the current server directory).
   Multiple arguments can be used to pass non-standard options to the
   ``LIST`` command.  If the last argument is a function, it is used
   as a *callback* function as for ``retrlines()``; the default prints
   to ``sys.stdout``.  This method returns ``None``.

FTP.rename(fromname, toname)

   Rename file *fromname* on the server to *toname*.

FTP.delete(filename)

   Remove the file named *filename* from the server.  If successful,
   returns the text of the response, otherwise raises ``error_perm``
   on permission errors or ``error_reply`` on other errors.

FTP.cwd(pathname)

   Set the current directory on the server.

FTP.mkd(pathname)

   Create a new directory on the server.

FTP.pwd()

   Return the pathname of the current directory on the server.

FTP.rmd(dirname)

   Remove the directory named *dirname* on the server.

FTP.size(filename)

   Request the size of the file named *filename* on the server.  On
   success, the size of the file is returned as an integer, otherwise
   ``None`` is returned. Note that the ``SIZE`` command is not
   standardized, but is supported by many common server
   implementations.

FTP.quit()

   Send a ``QUIT`` command to the server and close the connection.
   This is the "polite" way to close a connection, but it may raise an
   exception if the server responds with an error to the ``QUIT``
   command.  This implies a call to the ``close()`` method which
   renders the ``FTP`` instance useless for subsequent calls (see
   below).

FTP.close()

   Close the connection unilaterally.  This should not be applied to
   an already closed connection such as after a successful call to
   ``quit()``.  After this call the ``FTP`` instance should not be
   used any more (after a call to ``close()`` or ``quit()`` you cannot
   reopen the connection by issuing another ``login()`` method).
