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