Ubuntu Manpage: ftp - Client-side tcl implementation of the ftp protocol

NAME

       ftp - Client-side tcl implementation of the ftp protocol

SYNOPSIS

       package require Tcl  8.2

       package require ftp  ?2.4.13?

       ::ftp::Open server user passwd ?options?

       ::ftp::Close handle

       ::ftp::Cd handle directory

       ::ftp::Pwd handle

       ::ftp::Type handle ?ascii|binary|tenex?

       ::ftp::List handle ?pattern?

       ::ftp::NList handle ?directory?

       ::ftp::FileSize handle file

       ::ftp::ModTime handle file

       ::ftp::Delete handle file

       ::ftp::Rename handle from to

       ::ftp::Put handle (local | -data data | -channel chan) ?remote?

       ::ftp::Append handle (local | -data data | -channel chan) ?remote?

       ::ftp::Get handle remote ?(local | -variable varname | -channel chan)?

       ::ftp::Reget handle remote ?local? ?from? ?to?

       ::ftp::Newer handle remote ?local?

       ::ftp::MkDir handle directory

       ::ftp::RmDir handle directory

       ::ftp::Quote handle arg1 arg2 ...

       ::ftp::DisplayMsg handle msg ?state?

_________________________________________________________________________________________________

DESCRIPTION

       The  ftp  package  provides  the  client  side of the ftp protocol as specified in RFC 959
       (http://www.rfc-editor.org/rfc/rfc959.txt).  The package implements both active  (default)
       and passive ftp sessions.

       A  new  ftp  session  is started with the ::ftp::Open command. To shutdown an existing ftp
       session use ::ftp::Close. All other commands are restricted to usage in  an  an  open  ftp
       session.  They  will  generate  errors  if  they are used out of context.  The ftp package
       includes file and directory manipulating commands for remote sites. To  perform  the  same
       operations on the local site use commands built into the core, like cd or file.

       The  output  of  the  package  is  controlled  by  two state variables, ::ftp::VERBOSE and
       ::ftp::DEBUG. Setting ::ftp::VERBOSE to "1" forces the package to show all responses  from
       a  remote  server. The default value is "0". Setting ::ftp::DEBUG to "1" enables debugging
       and forces the package to show all return codes, states,  state  changes  and  "real"  ftp
       commands. The default value is "0".

       The command ::ftp::DisplayMsg is used to show the different messages from the ftp session.
       The setting of ::ftp::VERBOSE determines if this command is called  or  not.  The  current
       implementation  of  the  command  uses  the log package of tcllib to write the messages to
       their final destination. This  means  that  the  behaviour  of  ::ftp::DisplayMsg  can  be
       customized  without  changing its implementation. For more radical changes overwriting its
       implementation by the application is of course  still  possible.  Note  that  the  default
       implementation  honors  the  option  -output  to  ::ftp::Open  for  a session specific log
       command.

       Caution: The default implementation logs error messages like all other messages.  If  this
       behaviour  is  changed  to  throwing  an error instead all commands in the API will change
       their behaviour too. In such a case they will not return a failure code as described below
       but pass the thrown error to their caller.

API

::ftp::Open server user passwd ?options?
This command is used to start a FTP session by establishing a control connection to
the FTP server. The defaults are used for any option not specified by the caller.

The command takes a host name server, a user name user and a password password as
its parameters and returns a session handle that is an integer number greater than
or equal to "0", if the connection is successfully established. Otherwise it
returns "-1". The server parameter must be the name or internet address (in dotted
decimal notation) of the ftp server to connect to. The user and passwd parameters
must contain a valid user name and password to complete the login process.

The options overwrite some default values or set special abilities:

-blocksize size
The blocksize is used during data transfer. At most size bytes are
transfered at once. The default value for this option is 4096. The package
will evaluate the -progress callback for the session after the transfer of
each block.

-timeout seconds
If seconds is non-zero, then ::ftp::Open sets up a timeout which will occur
after the specified number of seconds. The default value is 600.

-port number
The port number specifies an alternative remote port on the ftp server on
which the ftp service resides. Most ftp services listen for connection
requests on the default port 21. Sometimes, usually for security reasons,
port numbers other than 21 are used for ftp connections.

-mode mode
The transfer mode option determines if a file transfer occurs in active or
passive mode. In passive mode the client will ask the ftp server to listen
on a data port and wait for the connection rather than to initiate the
process by itself when a data transfer request comes in. Passive mode is
normally a requirement when accessing sites via a firewall. The default mode
is active.

-progress callback
This callback is evaluated whenever a block of data was transfered. See the
option -blocksize for how to specify the size of the transfered blocks.

When evaluating the callback one argument is appended to the callback
script, the current accumulated number of bytes transferred so far.

-command callback
Specifying this option places the connection into asynchronous mode. The
callback is evaluated after the completion of any operation. When an
operation is running no further operations must be started until a callback
has been received for the currently executing operation.

When evaluating the callback several arguments are appended to the callback
script, namely the keyword of the operation that has completed and any
additional arguments specific to the operation. If an error occurred during
the execution of the operation the callback is given the keyword error.

-output callback
This option has no default. If it is set the default implementation of
::ftp::DisplayMsg will use its value as command prefix to log all internal
messages. The callback will have three arguments appended to it before
evaluation, the id of the session, the message itself, and the connection
state, in this order.

::ftp::Close handle
This command terminates the specified ftp session. If no file transfer is in
progress, the server will close the control connection immediately. If a file
transfer is in progress however, the control connection will remain open until the
transfers completes. When that happens the server will write the result response
for the transfer to it and close the connection afterward.

::ftp::Cd handle directory
This command changes the current working directory on the ftp server to a specified
target directory. The command returns 1 if the current working directory was
successfully changed to the specified directory or 0 if it fails. The target
directory can be

• a subdirectory of the current directory,

• Two dots, .. (as an indicator for the parent directory of the current
directory)

• or a fully qualified path to a new working directory.

::ftp::Pwd handle
This command returns the complete path of the current working directory on the ftp
server, or an empty string in case of an error.

::ftp::Type handle ?ascii|binary|tenex?
This command sets the ftp file transfer type to either ascii, binary, or tenex. The
command always returns the currently set type. If called without type no change is
made.

Currently only ascii and binary types are supported. There is some early (alpha)
support for Tenex mode. The type ascii is normally used to convert text files into
a format suitable for text editors on the platform of the destination machine. This
mainly affects end-of-line markers. The type binary on the other hand allows the
undisturbed transfer of non-text files, such as compressed files, images and
executables.

::ftp::List handle ?pattern?
This command returns a human-readable list of files. Wildcard expressions such as
"*.tcl" are allowed. If pattern refers to a specific directory, then the contents
of that directory are returned. If the pattern is not a fully-qualified path name,
the command lists entries relative to the current remote directory. If no pattern
is specified, the contents of the current remote directory is returned.

The listing includes any system-dependent information that the server chooses to
include. For example most UNIX systems produce output from the command ls -l. The
command returns the retrieved information as a tcl list with one item per entry.
Empty lines and UNIX's "total" lines are ignored and not included in the result as
reported by this command.

If the command fails an empty list is returned.

::ftp::NList handle ?directory?
This command has the same behavior as the ::ftp::List command, except that it only
retrieves an abbreviated listing. This means only file names are returned in a
sorted list.

::ftp::FileSize handle file
This command returns the size of the specified file on the ftp server. If the
command fails an empty string is returned.

ATTENTION! It will not work properly when in ascii mode and is not supported by all
ftp server implementations.

::ftp::ModTime handle file
This command retrieves the time of the last modification of the file on the ftp
server as a system dependent integer value in seconds or an empty string if an
error occurred. Use the built-in command clock to convert the retrieves value into
other formats.

::ftp::Delete handle file
This command deletes the specified file on the ftp server. The command returns 1 if
the specified file was successfully deleted or 0 if it failed.

::ftp::Rename handle from to
This command renames the file from in the current directory of the ftp server to
the specified new file name to. This new file name must not be the same as any
existing subdirectory or file name. The command returns 1 if the specified file
was successfully renamed or 0 if it failed.

::ftp::Put handle (local | -data data | -channel chan) ?remote?
This command transfers a local file local to a remote file remote on the ftp
server. If the file parameters passed to the command do not fully qualified path
names the command will use the current directory on local and remote host. If the
remote file name is unspecified, the server will use the name of the local file as
the name of the remote file. The command returns 1 to indicate a successful
transfer and 0 in the case of a failure.

If -data data is specified instead of a local file, the system will not transfer a
file, but the data passed into it. In this case the name of the remote file has to
be specified.

If -channel chan is specified instead of a local file, the system will not transfer
a file, but read the contents of the channel chan and write this to the remote
file. In this case the name of the remote file has to be specified. After the
transfer chan will be closed.

::ftp::Append handle (local | -data data | -channel chan) ?remote?
This command behaves like ::ftp::Puts, but appends the transfered information to
the remote file. If the file did not exist on the server it will be created.

::ftp::Get handle remote ?(local | -variable varname | -channel chan)?
This command retrieves a remote file remote on the ftp server and stores its
contents into the local file local. If the file parameters passed to the command
are not fully qualified path names the command will use the current directory on
local and remote host. If the local file name is unspecified, the server will use
the name of the remote file as the name of the local file. The command returns 1 to
indicate a successful transfer and 0 in the case of a failure. The command will
throw an error if the directory the file local is to be placed in does not exist.

If -variable varname is specified, the system will store the retrieved data into
the variable varname instead of a file.

If -channel chan is specified, the system will write the retrieved data into the
channel chan instead of a file. The system will not close chan after the transfer,
this is the responsibility of the caller to ::ftp::Get.

::ftp::Reget handle remote ?local? ?from? ?to?
This command behaves like ::ftp::Get, except that if local file local exists and is
smaller than remote file remote, the local file is presumed to be a partially
transferred copy of the remote file and the transfer is continued from the apparent
point of failure. The command will throw an error if the directory the file local
is to be placed in does not exist. This command is useful when transferring very
large files over networks that tend to drop connections.

Specifying the additional byte offsets from and to will cause the command to change
its behaviour and to download exactly the specified slice of the remote file. This
mode is possible only if a local destination is explicitly provided. Omission of to
leads to downloading till the end of the file.

::ftp::Newer handle remote ?local?
This command behaves like ::ftp::Get, except that it retrieves the remote file only
if the modification time of the remote file is more recent than the file on the
local system. If the file does not exist on the local system, the remote file is
considered newer. The command will throw an error if the directory the file local
is to be placed in does not exist.

::ftp::MkDir handle directory
This command creates the specified directory on the ftp server. If the specified
path is relative the new directory will be created as a subdirectory of the current
working directory. Else the created directory will have the specified path name.
The command returns 1 to indicate a successful creation of the directory and 0 in
the case of a failure.

::ftp::RmDir handle directory
This command removes the specified directory on the ftp server. The remote
directory has to be empty or the command will fail. The command returns 1 to
indicate a successful removal of the directory and 0 in the case of a failure.

::ftp::Quote handle arg1 arg2 ...
This command is used to send an arbitrary ftp command to the server. It cannot be
used to obtain a directory listing or for transferring files. It is included to
allow an application to execute commands on the ftp server which are not provided
by this package. The arguments are sent verbatim, i.e. as is, with no changes.

In contrast to the other commands in this package this command will not parse the
response it got from the ftp server but return it verbatim to the caller.

::ftp::DisplayMsg handle msg ?state?
This command is used by the package itself to show the different messages from the
ftp sessions. The package itself declares this command very simple, writing the
messages to stdout (if ::ftp::VERBOSE was set, see below) and throwing tcl errors
for error messages. It is the responsibility of the application to overwrite it as
needed. A state variable for different states assigned to different colors is
recommended by the author. The package log is useful for this.

::ftp::VERBOSE
A state variable controlling the output of the package. Setting ::ftp::VERBOSE to
"1" forces the package to show all responses from a remote server. The default
value is "0".

::ftp::DEBUG
A state variable controlling the output of ftp. Setting ::ftp::DEBUG to "1" enables
debugging and forces the package to show all return codes, states, state changes
and "real" ftp commands. The default value is "0".

BUGS

       The  correct  execution  of  many  commands depends upon the proper behavior by the remote
       server, network and router configuration.

       An update command placed in the procedure ::ftp::DisplayMsg may run into persistent errors
       or  infinite  loops.  The  solution  to this problem is to use update idletasks instead of
       update.

BUGS, IDEAS, FEEDBACK

       This document, and the package it describes,  will  undoubtedly  contain  bugs  and  other
       problems.    Please   report   such   in   the   category   ftp  of  the  Tcllib  Trackers
       [http://core.tcl.tk/tcllib/reportlist].  Please also report any ideas for enhancements you
       may have for either package and/or documentation.

KEYWORDS

       ftp, internet, net, rfc 959