Section: User Contributed Perl Documentation (3)
Net::Cmd - Network Command class (as used by FTP, SMTP etc)
@ISA = qw(Net::Cmd);
is a collection of methods that can be inherited by a sub-class
. These methods implement the functionality required for a
command based protocol, for example FTP
If your sub-class does not also derive from "IO::Socket::INET" or similar (e.g.
"IO::Socket::IP", "IO::Socket::INET6" or "IO::Socket::SSL") then you must
provide the following methods by other means yourself: "close()" and
These methods provide a user interface to the "Net::Cmd"
- debug ( VALUE )
Set the level of debug information for this object. If "VALUE" is not given
then the current state is returned. Otherwise the state is changed to
"VALUE" and the previous state returned.
may implement different levels of debug but a non-zero value results in
copies of all commands and responses also being sent to STDERR.
If "VALUE" is "undef" then the debug level will be set to the default
debug level for the class.
This method can also be called as a static method to set/get the default
debug level for a given class.
- message ()
Returns the text message returned from the last command. In a scalar
context it returns a single string, in a list context it will return
each line as a separate element. (See ``PSEUDO RESPONSES'' below.)
- code ()
Returns the 3-digit code from the last command. If a command is pending
then the value 0 is returned. (See ``PSEUDO RESPONSES'' below.)
- ok ()
Returns non-zero if the last code value was greater than zero and
less than 400. This holds true for most command servers. Servers
where this does not hold may override this method.
- status ()
Returns the most significant digit of the current status code. If a command
is pending then "CMD_PENDING" is returned.
- datasend ( DATA )
Send data to the remote server, converting LF to CRLF. Any line starting
with a '.' will be prefixed with another '.'.
"DATA" may be an array or a reference to an array.
The "DATA" passed in must be encoded by the caller to octets of whatever
encoding is required, e.g. by using the Encode module's "encode()" function.
- dataend ()
End the sending of data to the remote server. This is done by ensuring that
the data already sent ends with CRLF then sending '.CRLF' to end the
transmission. Once this data has been sent "dataend" calls "response" and
returns true if "response" returns CMD_OK.
These methods are not intended to be called by the user, but used or
over-ridden by a sub-class of "Net::Cmd"
- debug_print ( DIR, TEXT )
Print debugging information. "DIR" denotes the direction true being
data being sent to the server. Calls "debug_text" before printing to
- debug_text ( DIR, TEXT )
This method is called to print debugging information. TEXT is
the text being sent. The method should return the text to be printed.
This is primarily meant for the use of modules such as FTP where passwords
are sent, but we do not want to display them in the debugging information.
- command ( CMD [, ARGS, ... ])
Send a command to the command server. All arguments are first joined with
a space character and CRLF is appended, this string is then sent to the
Returns undef upon failure.
- unsupported ()
Sets the status code to 580 and the response text to 'Unsupported command'.
- response ()
Obtain a response from the server. Upon success the most significant digit
of the status code is returned. Upon failure, timeout etc., CMD_ERROR is
- parse_response ( TEXT )
This method is called by "response" as a method with one argument. It should
return an array of 2 values, the 3-digit status code and a flag which is true
when this is part of a multi-line response and this line is not the last.
- getline ()
Retrieve one line, delimited by CRLF, from the remote server. Returns undef
NOTE: If you do use this method for any reason, please remember to add
some "debug_print" calls into your method.
- ungetline ( TEXT )
Unget a line of text from the server.
- rawdatasend ( DATA )
Send data to the remote server without performing any conversions. "DATA"
is a scalar.
As with "datasend()", the "DATA" passed in must be encoded by the caller
to octets of whatever encoding is required, e.g. by using the Encode module's
- read_until_dot ()
Read data from the remote server until a line consisting of a single '.'.
Any lines starting with '..' will have one of the '.'s removed.
Returns a reference to a list containing the lines, or undef upon failure.
- tied_fh ()
Returns a filehandle tied to the Net::Cmd object. After issuing a
command, you may read from this filehandle using read() or <>. The
filehandle will return EOF when the final dot is encountered.
Similarly, you may write to the filehandle in order to send data to
the server after issuing a command that expects data to be written.
See the Net::POP3 and Net::SMTP modules for examples of this.
Normally the values returned by "message()"
obtained from the remote server, but in a few circumstances, as
detailed below, "Net::Cmd"
will return values that it sets. You
can alter this behavior by overriding DEF_REPLY_CODE()
a different default reply code, or overriding one of the specific
error handling methods below.
- Initial value
Before any command has executed or if an unexpected error occurs
"code()" will return ``421'' (temporary connection failure) and
"message()" will return undef.
- Connection closed
If the underlying "IO::Handle" is closed, or if there are
any read or write failures, the file handle will be forced closed,
and "code()" will return ``421'' (temporary connection failure)
and "message()" will return ``[$pkg] Connection closed''
(where $pkg is the name of the class that subclassed "Net::Cmd").
The _set_status_closed() method can be overridden to set a different
message (by calling set_status()) or otherwise trap this error.
If there is a read or write timeout "code()" will return ``421''
(temporary connection failure) and "message()" will return
``[$pkg] Timeout'' (where $pkg is the name of the class
that subclassed "Net::Cmd"). The _set_status_timeout() method
can be overridden to set a different message (by calling set_status())
or otherwise trap this error.
exports six subroutines, five of these, "CMD_INFO"
, correspond to possible results
. The sixth is "CMD_PENDING"
Graham Barr <email@example.com
Steve Hay <firstname.lastname@example.org> is now maintaining libnet as of version
Copyright (C) 1995-2006 Graham Barr. All rights reserved.
Copyright (C) 2013-2016 Steve Hay. All rights reserved.
This module is free software; you can redistribute it and/or modify it under the
same terms as Perl itself, i.e. under the terms of either the GNU
License or the Artistic License, as specified in the LICENCE