ftp(n) ftp client ftp(n)
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NAME
ftp - Client-side tcl implementation of the ftp protocol
SYNOPSIS
package require Tcl 8.2
package require ftp ?2.4.9?
::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?
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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 pack-
age 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 trans-
ferred 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 cur-
rently 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 oper-
ation 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
o a subdirectory of the current directory,
o Two dots, .. (as an indicator for the parent directory of the current directory)
o 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 spe-
cific 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 out-
put 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 sec-
onds 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 suc-
cessful 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 parame-
ters 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 speci-
fied 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 trans-
ferring 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 mes-
sages. It is the responsibility of the application to overwrite it as needed. A state variable for different states assigned to dif-
ferent 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 SF Trackers [http://sourceforge.net/tracker/?group_id=12883]. Please also report any ideas for enhancements you may have for
either package and/or documentation.
SEE ALSO
ftpd, mime, pop3, smtp
KEYWORDS
ftp, internet, net, rfc 959
CATEGORY
Networking
ftp 2.4.9 ftp(n)