Doc/lib/libftplib.tex

   1 \section{\module{ftplib} ---
   2          FTP protocol client}
   3
   4 \declaremodule{standard}{ftplib}
   5 \modulesynopsis{FTP protocol client (requires sockets).}
   6
   7 \indexii{FTP}{protocol}
   8 \index{FTP!\module{ftplib} (standard module)}
   9
  10 This module defines the class \class{FTP} and a few related items.
  11 The \class{FTP} class implements the client side of the FTP
  12 protocol.  You can use this to write Python
  13 programs that perform a variety of automated FTP jobs, such as
  14 mirroring other ftp servers.  It is also used by the module
  15 \refmodule{urllib} to handle URLs that use FTP.  For more information
  16 on FTP (File Transfer Protocol), see Internet \rfc{959}.
  17
  18 Here's a sample session using the \module{ftplib} module:
  19
  20 \begin{verbatim}
  21 >>> from ftplib import FTP
  22 >>> ftp = FTP('ftp.cwi.nl')   # connect to host, default port
  23 >>> ftp.login()               # user anonymous, passwd anonymous@
  24 >>> ftp.retrlines('LIST')     # list directory contents
  25 total 24418
  26 drwxrwsr-x   5 ftp-usr  pdmaint     1536 Mar 20 09:48 .
  27 dr-xr-srwt 105 ftp-usr  pdmaint     1536 Mar 21 14:32 ..
  28 -rw-r--r--   1 ftp-usr  pdmaint     5305 Mar 20 09:48 INDEX
  29  .
  30  .
  31  .
  32 >>> ftp.retrbinary('RETR README', open('README', 'wb').write)
  33 '226 Transfer complete.'
  34 >>> ftp.quit()
  35 \end{verbatim}
  36
  37 The module defines the following items:
  38
  39 \begin{classdesc}{FTP}{\optional{host\optional{, user\optional{,
  40                        passwd\optional{, acct}}}}}
  41 Return a new instance of the \class{FTP} class.  When
  42 \var{host} is given, the method call \code{connect(\var{host})} is
  43 made.  When \var{user} is given, additionally the method call
  44 \code{login(\var{user}, \var{passwd}, \var{acct})} is made (where
  45 \var{passwd} and \var{acct} default to the empty string when not given).
  46 \end{classdesc}
  47
  48 \begin{datadesc}{all_errors}
  49 The set of all exceptions (as a tuple) that methods of \class{FTP}
  50 instances may raise as a result of problems with the FTP connection
  51 (as opposed to programming errors made by the caller).  This set
  52 includes the four exceptions listed below as well as
  53 \exception{socket.error} and \exception{IOError}.
  54 \end{datadesc}
  55
  56 \begin{excdesc}{error_reply}
  57 Exception raised when an unexpected reply is received from the server.
  58 \end{excdesc}
  59
  60 \begin{excdesc}{error_temp}
  61 Exception raised when an error code in the range 400--499 is received.
  62 \end{excdesc}
  63
  64 \begin{excdesc}{error_perm}
  65 Exception raised when an error code in the range 500--599 is received.
  66 \end{excdesc}
  67
  68 \begin{excdesc}{error_proto}
  69 Exception raised when a reply is received from the server that does
  70 not begin with a digit in the range 1--5.
  71 \end{excdesc}
  72
  73
  74 \begin{seealso}
  75   \seemodule{netrc}{Parser for the \file{.netrc} file format.  The file
  76                     \file{.netrc} is typically used by FTP clients to
  77                     load user authentication information before prompting
  78                     the user.}
  79   \seetext{The file \file{Tools/scripts/ftpmirror.py}\index{ftpmirror.py}
  80            in the Python source distribution is a script that can mirror
  81            FTP sites, or portions thereof, using the \module{ftplib} module.
  82            It can be used as an extended example that applies this module.}
  83 \end{seealso}
  84
  85
  86 \subsection{FTP Objects \label{ftp-objects}}
  87
  88 Several methods are available in two flavors: one for handling text
  89 files and another for binary files.  These are named for the command
  90 which is used followed by \samp{lines} for the text version or
  91 \samp{binary} for the binary version.
  92
  93 \class{FTP} instances have the following methods:
  94
  95 \begin{methoddesc}{set_debuglevel}{level}
  96 Set the instance's debugging level.  This controls the amount of
  97 debugging output printed.  The default, \code{0}, produces no
  98 debugging output.  A value of \code{1} produces a moderate amount of
  99 debugging output, generally a single line per request.  A value of
 100 \code{2} or higher produces the maximum amount of debugging output,
 101 logging each line sent and received on the control connection.
 102 \end{methoddesc}
 103
 104 \begin{methoddesc}{connect}{host\optional{, port}}
 105 Connect to the given host and port.  The default port number is \code{21}, as
 106 specified by the FTP protocol specification.  It is rarely needed to
 107 specify a different port number.  This function should be called only
 108 once for each instance; it should not be called at all if a host was
 109 given when the instance was created.  All other methods can only be
 110 used after a connection has been made.
 111 \end{methoddesc}
 112
 113 \begin{methoddesc}{getwelcome}{}
 114 Return the welcome message sent by the server in reply to the initial
 115 connection.  (This message sometimes contains disclaimers or help
 116 information that may be relevant to the user.)
 117 \end{methoddesc}
 118
 119 \begin{methoddesc}{login}{\optional{user\optional{, passwd\optional{, acct}}}}
 120 Log in as the given \var{user}.  The \var{passwd} and \var{acct}
 121 parameters are optional and default to the empty string.  If no
 122 \var{user} is specified, it defaults to \code{'anonymous'}.  If
 123 \var{user} is \code{'anonymous'}, the default \var{passwd} is
 124 \code{'anonymous@'}.  This function should be called only
 125 once for each instance, after a connection has been established; it
 126 should not be called at all if a host and user were given when the
 127 instance was created.  Most FTP commands are only allowed after the
 128 client has logged in.
 129 \end{methoddesc}
 130
 131 \begin{methoddesc}{abort}{}
 132 Abort a file transfer that is in progress.  Using this does not always
 133 work, but it's worth a try.
 134 \end{methoddesc}
 135
 136 \begin{methoddesc}{sendcmd}{command}
 137 Send a simple command string to the server and return the response
 138 string.
 139 \end{methoddesc}
 140
 141 \begin{methoddesc}{voidcmd}{command}
 142 Send a simple command string to the server and handle the response.
 143 Return nothing if a response code in the range 200--299 is received.
 144 Raise an exception otherwise.
 145 \end{methoddesc}
 146
 147 \begin{methoddesc}{retrbinary}{command,
 148     callback\optional{, maxblocksize\optional{, rest}}}
 149 Retrieve a file in binary transfer mode.  \var{command} should be an
 150 appropriate \samp{RETR} command: \code{'RETR \var{filename}'}.
 151 The \var{callback} function is called for each block of data received,
 152 with a single string argument giving the data block.
 153 The optional \var{maxblocksize} argument specifies the maximum chunk size to
 154 read on the low-level socket object created to do the actual transfer
 155 (which will also be the largest size of the data blocks passed to
 156 \var{callback}).  A reasonable default is chosen. \var{rest} means the
 157 same thing as in the \method{transfercmd()} method.
 158 \end{methoddesc}
 159
 160 \begin{methoddesc}{retrlines}{command\optional{, callback}}
 161 Retrieve a file or directory listing in \ASCII{} transfer mode.
 162 \var{command} should be an appropriate \samp{RETR} command (see
 163 \method{retrbinary()} or a \samp{LIST} command (usually just the string
 164 \code{'LIST'}).  The \var{callback} function is called for each line,
 165 with the trailing CRLF stripped.  The default \var{callback} prints
 166 the line to \code{sys.stdout}.
 167 \end{methoddesc}
 168
 169 \begin{methoddesc}{set_pasv}{boolean}
 170 Enable ``passive'' mode if \var{boolean} is true, other disable
 171 passive mode.  (In Python 2.0 and before, passive mode was off by
 172 default; in Python 2.1 and later, it is on by default.)
 173 \end{methoddesc}
 174
 175 \begin{methoddesc}{storbinary}{command, file\optional{, blocksize}}
 176 Store a file in binary transfer mode.  \var{command} should be an
 177 appropriate \samp{STOR} command: \code{"STOR \var{filename}"}.
 178 \var{file} is an open file object which is read until \EOF{} using its
 179 \method{read()} method in blocks of size \var{blocksize} to provide the
 180 data to be stored.  The \var{blocksize} argument defaults to 8192.
 181 \versionchanged[default for \var{blocksize} added]{2.1}
 182 \end{methoddesc}
 183
 184 \begin{methoddesc}{storlines}{command, file}
 185 Store a file in \ASCII{} transfer mode.  \var{command} should be an
 186 appropriate \samp{STOR} command (see \method{storbinary()}).  Lines are
 187 read until \EOF{} from the open file object \var{file} using its
 188 \method{readline()} method to provide the data to be stored.
 189 \end{methoddesc}
 190
 191 \begin{methoddesc}{transfercmd}{cmd\optional{, rest}}
 192 Initiate a transfer over the data connection.  If the transfer is
 193 active, send a \samp{EPRT} or  \samp{PORT} command and the transfer command specified
 194 by \var{cmd}, and accept the connection.  If the server is passive,
 195 send a \samp{EPSV} or \samp{PASV} command, connect to it, and start the transfer
 196 command.  Either way, return the socket for the connection.
 197
 198 If optional \var{rest} is given, a \samp{REST} command is
 199 sent to the server, passing \var{rest} as an argument.  \var{rest} is
 200 usually a byte offset into the requested file, telling the server to
 201 restart sending the file's bytes at the requested offset, skipping
 202 over the initial bytes.  Note however that RFC
 203 959 requires only that \var{rest} be a string containing characters
 204 in the printable range from ASCII code 33 to ASCII code 126.  The
 205 \method{transfercmd()} method, therefore, converts
 206 \var{rest} to a string, but no check is
 207 performed on the string's contents.  If the server does
 208 not recognize the \samp{REST} command, an
 209 \exception{error_reply} exception will be raised.  If this happens,
 210 simply call \method{transfercmd()} without a \var{rest} argument.
 211 \end{methoddesc}
 212
 213 \begin{methoddesc}{ntransfercmd}{cmd\optional{, rest}}
 214 Like \method{transfercmd()}, but returns a tuple of the data
 215 connection and the expected size of the data.  If the expected size
 216 could not be computed, \code{None} will be returned as the expected
 217 size.  \var{cmd} and \var{rest} means the same thing as in
 218 \method{transfercmd()}.
 219 \end{methoddesc}
 220
 221 \begin{methoddesc}{nlst}{argument\optional{, \ldots}}
 222 Return a list of files as returned by the \samp{NLST} command.  The
 223 optional \var{argument} is a directory to list (default is the current
 224 server directory).  Multiple arguments can be used to pass
 225 non-standard options to the \samp{NLST} command.
 226 \end{methoddesc}
 227
 228 \begin{methoddesc}{dir}{argument\optional{, \ldots}}
 229 Produce a directory listing as returned by the \samp{LIST} command,
 230 printing it to standard output.  The optional \var{argument} is a
 231 directory to list (default is the current server directory).  Multiple
 232 arguments can be used to pass non-standard options to the \samp{LIST}
 233 command.  If the last argument is a function, it is used as a
 234 \var{callback} function as for \method{retrlines()}; the default
 235 prints to \code{sys.stdout}.  This method returns \code{None}.
 236 \end{methoddesc}
 237
 238 \begin{methoddesc}{rename}{fromname, toname}
 239 Rename file \var{fromname} on the server to \var{toname}.
 240 \end{methoddesc}
 241
 242 \begin{methoddesc}{delete}{filename}
 243 Remove the file named \var{filename} from the server.  If successful,
 244 returns the text of the response, otherwise raises
 245 \exception{error_perm} on permission errors or
 246 \exception{error_reply} on other errors.
 247 \end{methoddesc}
 248
 249 \begin{methoddesc}{cwd}{pathname}
 250 Set the current directory on the server.
 251 \end{methoddesc}
 252
 253 \begin{methoddesc}{mkd}{pathname}
 254 Create a new directory on the server.
 255 \end{methoddesc}
 256
 257 \begin{methoddesc}{pwd}{}
 258 Return the pathname of the current directory on the server.
 259 \end{methoddesc}
 260
 261 \begin{methoddesc}{rmd}{dirname}
 262 Remove the directory named \var{dirname} on the server.
 263 \end{methoddesc}
 264
 265 \begin{methoddesc}{size}{filename}
 266 Request the size of the file named \var{filename} on the server.  On
 267 success, the size of the file is returned as an integer, otherwise
 268 \code{None} is returned.  Note that the \samp{SIZE} command is not
 269 standardized, but is supported by many common server implementations.
 270 \end{methoddesc}
 271
 272 \begin{methoddesc}{quit}{}
 273 Send a \samp{QUIT} command to the server and close the connection.
 274 This is the ``polite'' way to close a connection, but it may raise an
 275 exception of the server reponds with an error to the
 276 \samp{QUIT} command.  This implies a call to the \method{close()}
 277 method which renders the \class{FTP} instance useless for subsequent
 278 calls (see below).
 279 \end{methoddesc}
 280
 281 \begin{methoddesc}{close}{}
 282 Close the connection unilaterally.  This should not be applied to an
 283 already closed connection (such as after a successful call to
 284 \method{quit()}.  After this call the \class{FTP} instance should not
 285 be used any more (after a call to \method{close()} or
 286 \method{quit()} you cannot reopen the connection by issuing another
 287 \method{login()} method).
 288 \end{methoddesc}