271 lines
11 KiB
TeX
271 lines
11 KiB
TeX
\section{\module{ftplib} ---
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FTP protocol client}
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\declaremodule{standard}{ftplib}
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\modulesynopsis{FTP protocol client (requires sockets).}
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This module defines the class \class{FTP} and a few related items.
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The \class{FTP} class implements the client side of the FTP
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protocol.\indexii{FTP}{protocol} You can use this to write Python
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programs that perform a variety of automated FTP jobs, such as
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mirroring other ftp servers. It is also used by the module
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\refmodule{urllib} to handle URLs that use FTP. For more information
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on FTP (File Transfer Protocol), see Internet \rfc{959}.
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Here's a sample session using the \module{ftplib} module:
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\begin{verbatim}
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>>> from ftplib import FTP
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>>> ftp = FTP('ftp.cwi.nl') # connect to host, default port
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>>> ftp.login() # user anonymous, passwd user@hostname
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>>> ftp.retrlines('LIST') # list directory contents
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total 24418
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drwxrwsr-x 5 ftp-usr pdmaint 1536 Mar 20 09:48 .
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dr-xr-srwt 105 ftp-usr pdmaint 1536 Mar 21 14:32 ..
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-rw-r--r-- 1 ftp-usr pdmaint 5305 Mar 20 09:48 INDEX
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.
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.
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.
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>>> ftp.retrbinary('RETR README', open('README', 'wb').write)
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'226 Transfer complete.'
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>>> ftp.quit()
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\end{verbatim}
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The module defines the following items:
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\begin{classdesc}{FTP}{\optional{host\optional{, user\optional{,
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passwd\optional{, acct}}}}}
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Return a new instance of the \class{FTP} class. When
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\var{host} is given, the method call \code{connect(\var{host})} is
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made. When \var{user} is given, additionally the method call
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\code{login(\var{user}, \var{passwd}, \var{acct})} is made (where
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\var{passwd} and \var{acct} default to the empty string when not given).
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\end{classdesc}
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\begin{datadesc}{all_errors}
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The set of all exceptions (as a tuple) that methods of \class{FTP}
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instances may raise as a result of problems with the FTP connection
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(as opposed to programming errors made by the caller). This set
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includes the four exceptions listed below as well as
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\exception{socket.error} and \exception{IOError}.
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\end{datadesc}
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\begin{excdesc}{error_reply}
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Exception raised when an unexpected reply is received from the server.
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\end{excdesc}
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\begin{excdesc}{error_temp}
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Exception raised when an error code in the range 400--499 is received.
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\end{excdesc}
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\begin{excdesc}{error_perm}
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Exception raised when an error code in the range 500--599 is received.
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\end{excdesc}
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\begin{excdesc}{error_proto}
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Exception raised when a reply is received from the server that does
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not begin with a digit in the range 1--5.
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\end{excdesc}
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\begin{seealso}
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\seemodule{netrc}{Parser for the \file{.netrc} file format. The file
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\file{.netrc} is typically used by FTP clients to
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load user authentication information before prompting
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the user.}
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\seetext{The file \file{Tools/scripts/ftpmirror.py}\index{ftpmirror.py}
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in the Python source distribution is a script that can mirror
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FTP sites, or portions thereof, using the \module{ftplib} module.
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It can be used as an extended example that applies this module.}
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\end{seealso}
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\subsection{FTP Objects \label{ftp-objects}}
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Several methods are available in two flavors: one for handling text
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files and another for binary files. These are named for the command
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which is used followed by \samp{lines} for the text version or
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\samp{binary} for the binary version.
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\class{FTP} instances have the following methods:
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\begin{methoddesc}{set_debuglevel}{level}
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Set the instance's debugging level. This controls the amount of
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debugging output printed. The default, \code{0}, produces no
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debugging output. A value of \code{1} produces a moderate amount of
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debugging output, generally a single line per request. A value of
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\code{2} or higher produces the maximum amount of debugging output,
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logging each line sent and received on the control connection.
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\end{methoddesc}
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\begin{methoddesc}{connect}{host\optional{, port}}
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Connect to the given host and port. The default port number is \code{21}, as
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specified by the FTP protocol specification. It is rarely needed to
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specify a different port number. This function should be called only
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once for each instance; it should not be called at all if a host was
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given when the instance was created. All other methods can only be
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used after a connection has been made.
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\end{methoddesc}
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\begin{methoddesc}{getwelcome}{}
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Return the welcome message sent by the server in reply to the initial
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connection. (This message sometimes contains disclaimers or help
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information that may be relevant to the user.)
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\end{methoddesc}
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\begin{methoddesc}{login}{\optional{user\optional{, passwd\optional{, acct}}}}
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Log in as the given \var{user}. The \var{passwd} and \var{acct}
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parameters are optional and default to the empty string. If no
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\var{user} is specified, it defaults to \code{'anonymous'}. If
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\var{user} is \code{'anonymous'}, the default \var{passwd} is
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\samp{\var{realuser}@\var{host}} where \var{realuser} is the real user
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name (glanced from the \envvar{LOGNAME} or \envvar{USER} environment
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variable) and \var{host} is the hostname as returned by
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\function{socket.gethostname()}. This function should be called only
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once for each instance, after a connection has been established; it
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should not be called at all if a host and user were given when the
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instance was created. Most FTP commands are only allowed after the
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client has logged in.
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\end{methoddesc}
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\begin{methoddesc}{abort}{}
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Abort a file transfer that is in progress. Using this does not always
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work, but it's worth a try.
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\end{methoddesc}
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\begin{methoddesc}{sendcmd}{command}
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Send a simple command string to the server and return the response
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string.
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\end{methoddesc}
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\begin{methoddesc}{voidcmd}{command}
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Send a simple command string to the server and handle the response.
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Return nothing if a response code in the range 200--299 is received.
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Raise an exception otherwise.
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\end{methoddesc}
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\begin{methoddesc}{retrbinary}{command, callback\optional{, maxblocksize}}
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Retrieve a file in binary transfer mode. \var{command} should be an
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appropriate \samp{RETR} command, i.e.\ \code{'RETR \var{filename}'}.
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The \var{callback} function is called for each block of data received,
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with a single string argument giving the data block.
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The optional \var{maxblocksize} argument specifies the maximum chunk size to
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read on the low-level socket object created to do the actual transfer
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(which will also be the largest size of the data blocks passed to
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\var{callback}). A reasonable default is chosen.
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\end{methoddesc}
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\begin{methoddesc}{retrlines}{command\optional{, callback}}
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Retrieve a file or directory listing in \ASCII{} transfer mode.
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\var{command} should be an appropriate \samp{RETR} command (see
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\method{retrbinary()} or a \samp{LIST} command (usually just the string
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\code{'LIST'}). The \var{callback} function is called for each line,
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with the trailing CRLF stripped. The default \var{callback} prints
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the line to \code{sys.stdout}.
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\end{methoddesc}
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\begin{methoddesc}{set_pasv}{boolean}
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Enable ``passive'' mode if \var{boolean} is true, other disable
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passive mode.
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\end{methoddesc}
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\begin{methoddesc}{storbinary}{command, file, blocksize}
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Store a file in binary transfer mode. \var{command} should be an
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appropriate \samp{STOR} command, i.e.\ \code{"STOR \var{filename}"}.
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\var{file} is an open file object which is read until \EOF{} using its
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\method{read()} method in blocks of size \var{blocksize} to provide the
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data to be stored.
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\end{methoddesc}
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\begin{methoddesc}{storlines}{command, file}
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Store a file in \ASCII{} transfer mode. \var{command} should be an
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appropriate \samp{STOR} command (see \method{storbinary()}). Lines are
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read until \EOF{} from the open file object \var{file} using its
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\method{readline()} method to provide the data to be stored.
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\end{methoddesc}
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\begin{methoddesc}{transfercmd}{cmd}
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Initiate a transfer over the data connection. If the transfer is
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active, send a \samp{PORT} command and the transfer command specified
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by \var{cmd}, and accept the connection. If the server is passive,
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send a \samp{PASV} command, connect to it, and start the transfer
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command. Either way, return the socket for the connection.
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\end{methoddesc}
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\begin{methoddesc}{ntransfercmd}{cmd}
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Like \method{transfercmd()}, but returns a tuple of the data
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connection and the expected size of the data. If the expected size
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could not be computed, \code{None} will be returned as the expected
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size.
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\end{methoddesc}
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\begin{methoddesc}{nlst}{argument\optional{, \ldots}}
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Return a list of files as returned by the \samp{NLST} command. The
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optional \var{argument} is a directory to list (default is the current
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server directory). Multiple arguments can be used to pass
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non-standard options to the \samp{NLST} command.
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\end{methoddesc}
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\begin{methoddesc}{dir}{argument\optional{, \ldots}}
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Produce a directory listing as returned by the \samp{LIST} command,
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printing it to standard output. The optional \var{argument} is a
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directory to list (default is the current server directory). Multiple
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arguments can be used to pass non-standard options to the \samp{LIST}
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command. If the last argument is a function, it is used as a
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\var{callback} function as for \method{retrlines()}; the default
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prints to \code{sys.stdout}. This method returns \code{None}.
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\end{methoddesc}
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\begin{methoddesc}{rename}{fromname, toname}
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Rename file \var{fromname} on the server to \var{toname}.
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\end{methoddesc}
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\begin{methoddesc}{delete}{filename}
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Remove the file named \var{filename} from the server. If successful,
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returns the text of the response, otherwise raises
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\exception{error_perm} on permission errors or
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\exception{error_reply} on other errors.
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\end{methoddesc}
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\begin{methoddesc}{cwd}{pathname}
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Set the current directory on the server.
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\end{methoddesc}
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\begin{methoddesc}{mkd}{pathname}
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Create a new directory on the server.
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\end{methoddesc}
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\begin{methoddesc}{pwd}{}
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Return the pathname of the current directory on the server.
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\end{methoddesc}
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\begin{methoddesc}{rmd}{dirname}
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Remove the directory named \var{dirname} on the server.
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\end{methoddesc}
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\begin{methoddesc}{size}{filename}
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Request the size of the file named \var{filename} on the server. On
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success, the size of the file is returned as an integer, otherwise
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\code{None} is returned. Note that the \samp{SIZE} command is not
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standardized, but is supported by many common server implementations.
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\end{methoddesc}
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\begin{methoddesc}{quit}{}
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Send a \samp{QUIT} command to the server and close the connection.
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This is the ``polite'' way to close a connection, but it may raise an
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exception of the server reponds with an error to the
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\samp{QUIT} command. This implies a call to the \method{close()}
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method which renders the \class{FTP} instance useless for subsequent
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calls (see below).
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\end{methoddesc}
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\begin{methoddesc}{close}{}
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Close the connection unilaterally. This should not be applied to an
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already closed connection (e.g.\ after a successful call to
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\method{quit()}. After this call the \class{FTP} instance should not
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be used any more (i.e., after a call to \method{close()} or
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\method{quit()} you cannot reopen the connection by issuing another
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\method{login()} method).
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\end{methoddesc}
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