net::ftp.3

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

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.\" ========================================================================
.\"
.IX Title "Net::FTP 3"
.TH Net::FTP 3 "2007-12-18" "perl v5.10.0" "Perl Programmers Reference Guide"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
Net::FTP \- FTP Client class
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&    use Net::FTP;
\&
\&    $ftp = Net::FTP\->new("some.host.name", Debug => 0)
\&      or die "Cannot connect to some.host.name: $@";
\&
\&    $ftp\->login("anonymous",\*(Aq\-anonymous@\*(Aq)
\&      or die "Cannot login ", $ftp\->message;
\&
\&    $ftp\->cwd("/pub")
\&      or die "Cannot change working directory ", $ftp\->message;
\&
\&    $ftp\->get("that.file")
\&      or die "get failed ", $ftp\->message;
\&
\&    $ftp\->quit;
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\f(CW\*(C`Net::FTP\*(C'\fR is a class implementing a simple \s-1FTP\s0 client in Perl as
described in \s-1RFC959\s0.  It provides wrappers for a subset of the \s-1RFC959\s0
commands.
.SH "OVERVIEW"
.IX Header "OVERVIEW"
\&\s-1FTP\s0 stands for File Transfer Protocol.  It is a way of transferring
files between networked machines.  The protocol defines a client
(whose commands are provided by this module) and a server (not
implemented in this module).  Communication is always initiated by the
client, and the server responds with a message and a status code (and
sometimes with data).
.PP
The \s-1FTP\s0 protocol allows files to be sent to or fetched from the
server.  Each transfer involves a \fBlocal file\fR (on the client) and a
\&\fBremote file\fR (on the server).  In this module, the same file name
will be used for both local and remote if only one is specified.  This
means that transferring remote file \f(CW\*(C`/path/to/file\*(C'\fR will try to put
that file in \f(CW\*(C`/path/to/file\*(C'\fR locally, unless you specify a local file
name.
.PP
The protocol also defines several standard \fBtranslations\fR which the
file can undergo during transfer.  These are \s-1ASCII\s0, \s-1EBCDIC\s0, binary,
and byte.  \s-1ASCII\s0 is the default type, and indicates that the sender of
files will translate the ends of lines to a standard representation
which the receiver will then translate back into their local
representation.  \s-1EBCDIC\s0 indicates the file being transferred is in
\&\s-1EBCDIC\s0 format.  Binary (also known as image) format sends the data as
a contiguous bit stream.  Byte format transfers the data as bytes, the
values of which remain the same regardless of differences in byte size
between the two machines (in theory \- in practice you should only use
this if you really know what you're doing).
.SH "CONSTRUCTOR"
.IX Header "CONSTRUCTOR"
.IP "new ([ \s-1HOST\s0 ] [, \s-1OPTIONS\s0 ])" 4
.IX Item "new ([ HOST ] [, OPTIONS ])"
This is the constructor for a new Net::FTP object. \f(CW\*(C`HOST\*(C'\fR is the
name of the remote host to which an \s-1FTP\s0 connection is required.
.Sp
\&\f(CW\*(C`HOST\*(C'\fR is optional. If \f(CW\*(C`HOST\*(C'\fR is not given then it may instead be
passed as the \f(CW\*(C`Host\*(C'\fR option described below.
.Sp
\&\f(CW\*(C`OPTIONS\*(C'\fR are passed in a hash like fashion, using key and value pairs.
Possible options are:
.Sp
\&\fBHost\fR \- \s-1FTP\s0 host to connect to. It may be a single scalar, as defined for
the \f(CW\*(C`PeerAddr\*(C'\fR option in IO::Socket::INET, or a reference to
an array with hosts to try in turn. The \*(L"host\*(R" method will return the value
which was used to connect to the host.
.Sp
\&\fBFirewall\fR \- The name of a machine which acts as an \s-1FTP\s0 firewall. This can be
overridden by an environment variable \f(CW\*(C`FTP_FIREWALL\*(C'\fR. If specified, and the
given host cannot be directly connected to, then the
connection is made to the firewall machine and the string \f(CW@hostname\fR is
appended to the login identifier. This kind of setup is also referred to
as an ftp proxy.
.Sp
\&\fBFirewallType\fR \- The type of firewall running on the machine indicated by
\&\fBFirewall\fR. This can be overridden by an environment variable
\&\f(CW\*(C`FTP_FIREWALL_TYPE\*(C'\fR. For a list of permissible types, see the description of
ftp_firewall_type in Net::Config.
.Sp
\&\fBBlockSize\fR \- This is the block size that Net::FTP will use when doing
transfers. (defaults to 10240)
.Sp
\&\fBPort\fR \- The port number to connect to on the remote machine for the
\&\s-1FTP\s0 connection
.Sp
\&\fBTimeout\fR \- Set a timeout value (defaults to 120)
.Sp
\&\fBDebug\fR \- debug level (see the debug method in Net::Cmd)
.Sp
\&\fBPassive\fR \- If set to a non-zero value then all data transfers will
be done using passive mode. If set to zero then data transfers will be
done using active mode.  If the machine is connected to the Internet
directly, both passive and active mode should work equally well.
Behind most firewall and \s-1NAT\s0 configurations passive mode has a better
chance of working.  However, in some rare firewall configurations,
active mode actually works when passive mode doesn't.  Some really old
\&\s-1FTP\s0 servers might not implement passive transfers.  If not specified,
then the transfer mode is set by the environment variable
\&\f(CW\*(C`FTP_PASSIVE\*(C'\fR or if that one is not set by the settings done by the
\&\fIlibnetcfg\fR utility.  If none of these apply then passive mode is
used.
.Sp
\&\fBHash\fR \- If given a reference to a file handle (e.g., \f(CW\*(C`\e*STDERR\*(C'\fR),
print hash marks (#) on that filehandle every 1024 bytes.  This
simply invokes the \f(CW\*(C`hash()\*(C'\fR method for you, so that hash marks
are displayed for all transfers.  You can, of course, call \f(CW\*(C`hash()\*(C'\fR
explicitly whenever you'd like.
.Sp
\&\fBLocalAddr\fR \- Local address to use for all socket connections, this
argument will be passed to IO::Socket::INET
.Sp
If the constructor fails undef will be returned and an error message will
be in $@
.SH "METHODS"
.IX Header "METHODS"
Unless otherwise stated all methods return either a \fItrue\fR or \fIfalse\fR
value, with \fItrue\fR meaning that the operation was a success. When a method
states that it returns a value, failure will be returned as \fIundef\fR or an
empty list.
.IP "login ([\s-1LOGIN\s0 [,PASSWORD [, \s-1ACCOUNT\s0] ] ])" 4
.IX Item "login ([LOGIN [,PASSWORD [, ACCOUNT] ] ])"
Log into the remote \s-1FTP\s0 server with the given login information. If
no arguments are given then the \f(CW\*(C`Net::FTP\*(C'\fR uses the \f(CW\*(C`Net::Netrc\*(C'\fR
package to lookup the login information for the connected host.
If no information is found then a login of \fIanonymous\fR is used.
If no password is given and the login is \fIanonymous\fR then \fIanonymous@\fR
will be used for password.
.Sp
If the connection is via a firewall then the \f(CW\*(C`authorize\*(C'\fR method will
be called with no arguments.
.IP "authorize ( [\s-1AUTH\s0 [, \s-1RESP\s0]])" 4
.IX Item "authorize ( [AUTH [, RESP]])"
This is a protocol used by some firewall ftp proxies. It is used
to authorise the user to send data out.  If both arguments are not specified
then \f(CW\*(C`authorize\*(C'\fR uses \f(CW\*(C`Net::Netrc\*(C'\fR to do a lookup.
.IP "site (\s-1ARGS\s0)" 4
.IX Item "site (ARGS)"
Send a \s-1SITE\s0 command to the remote server and wait for a response.
.Sp
Returns most significant digit of the response code.
.IP "ascii" 4
.IX Item "ascii"
Transfer file in \s-1ASCII\s0. \s-1CRLF\s0 translation will be done if required
.IP "binary" 4
.IX Item "binary"
Transfer file in binary mode. No transformation will be done.
.Sp
\&\fBHint\fR: If both server and client machines use the same line ending for
text files, then it will be faster to transfer all files in binary mode.
.IP "rename ( \s-1OLDNAME\s0, \s-1NEWNAME\s0 )" 4
.IX Item "rename ( OLDNAME, NEWNAME )"
Rename a file on the remote \s-1FTP\s0 server from \f(CW\*(C`OLDNAME\*(C'\fR to \f(CW\*(C`NEWNAME\*(C'\fR. This
is done by sending the \s-1RNFR\s0 and \s-1RNTO\s0 commands.
.IP "delete ( \s-1FILENAME\s0 )" 4
.IX Item "delete ( FILENAME )"
Send a request to the server to delete \f(CW\*(C`FILENAME\*(C'\fR.
.IP "cwd ( [ \s-1DIR\s0 ] )" 4
.IX Item "cwd ( [ DIR ] )"
Attempt to change directory to the directory given in \f(CW$dir\fR.  If
\&\f(CW$dir\fR is \f(CW".."\fR, the \s-1FTP\s0 \f(CW\*(C`CDUP\*(C'\fR command is used to attempt to
move up one directory. If no directory is given then an attempt is made
to change the directory to the root directory.
.IP "cdup ()" 4
.IX Item "cdup ()"