By Vikram Vaswani
Melonfire
November 07, 2000
We are a group of loyal fans of PHP. We use it for various reasons - WEB site development, drawing, database connection, etc. - we found that, It's very friendly, powerful and easy to use...
You may have seen how PHP is used to create GIF and JPEG images, dynamically obtain information from databases, etc., but this is just the tip of the iceberg --- The latest version of PHP has powerful file transfer capabilities.
In this tutorial, I will show you how FTP transfers files through HTTP and FTP connections. There will also be some simple program codes. Follow me!

First of all, you should know that PHP transfers files through HTTP and FTP connections. Uploading files through HTTP has already appeared in PHP3, and now, the new FTP function has appeared in the new PHP version!
Before you start, you need to make sure that your PHP supports FTP. You can check this through the following code:

--------------------- -------------------------------------------------- ----------

phpinfo();

?>
------------- -------------------------------------------------- ------------------
Check the output results, there is an "Additional Modules" area, which lists the modules supported by your PHP; if you do not find the FTP module, you Best to reinstall PHP and add FTP support!

First let’s take a look at how a typical FTP task is completed!
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$ ftp ftp.server.com
Connected to ftp. server.com
220 server.com FTP server ready.
Name (server:john): john
331 Password required for john.
Password:
230 User john logged in.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> ls
200 PORT command successful.
150 Opening ASCII mode data connection for /bin/ls.
drwxr -xr-x 5 john users 3072 Nov 2 11:03 .
drwxr-xr-x 88 root root 2048 Nov 1 23:26 ..
drwxr--r-- 2 john users 1024 Oct 5 13: 26 bin
drwx--x--x 8 john users 1024 Nov 2 10:59 public_html
drwxr--r-- 4 john users 1024 Nov 2 11:26 tmp
-rw-r-- r-- 1 john users 2941465 Oct 9 17:21 data.zip
226 Transfer complete.
ftp> bin
200 Type set to I.
ftp> get data.zip
local : data.zip remote: data.zip
200 PORT command successful.
150 Opening BINARY mode data connection for data.zip(2941465 bytes).
226 Transfer complete.
ftp> bye
221 Goodbye.
------------------------------------------------ ----------------------------------------
You can see that the process is clearly divided into Several paragraphs: connection (establishing a connection with the FTP server), verification (determining whether the user has the authority to enter the system), transmission (this includes listing directories, uploading or downloading files), and canceling the connection.

Steps to use PHP for FTP
Establishing a PHP FTP connection must follow the following basic steps: Open a connection - Issue authentication information - Use PHP functions to manipulate directories and transfer files.
The following specific implementation:
---------------------------------------- ----------------------------------------

// Connect to FTP server
$conn = ftp_connect("ftp.server.com");

// Log in using username and password
ftp_login($conn, "john", " doe");

// Get the remote system type
ftp_systype($conn);

// List files
$filelist = ftp_nlist($conn, ". ");

// Download file
ftp_get($conn, "data.zip", "data.zip", FTP_BINARY);

// Close the connection
ftp_quit ($conn);

?>
--------------------------------- --------------------------------------------------
Let's do it step by step:
To initialize an FTP connection, PHP provides the ftp_connect() function, which takes the host name and port as parameters. In the above example, the host name is "ftp.server.com"; if the port is not specified, PHP will use "21" as the default port to establish the connection.
After the connection is successful, ftp_connect() returns a handle; this handle will be used by the FTP function used later.
-------------------------------------------------- ----------------------------------

// connect to FTP server
$conn = ftp_connect("ftp.server.com");

?>
-------------------------- -------------------------------------------------- ----------
Once the connection is established, use ftp_login() to send a username and user password.You can see that the function ftp_login() uses the handle passed by the ftp_connect() function to determine that the username and password can be submitted to the correct server.
-------------------------------------------------- ----------------------------------

// log in with username and password
ftp_login($conn, "john", "doe");

?>
------------------ -------------------------------------------------- ------------
At this time, you can do what you want to do. The details will be explained in the next part:

After you finish what you want to do, Remember to use the ftp_quit() function to close your FTP connection

-------------------------------- --------------------------------------------------

// close connection
ftp_quit($conn);

?>
------------- -------------------------------------------------- ----------------
Log in to the FTP server. PHP provides some functions that can obtain some information about the system, files and directories.

ftp_pwd()
If you want to know the directory you are currently in, you need to use this function.
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// get current location
$here = ftp_pwd($conn);

?>
-------------------------- -------------------------------------------------- ----
What if you need to know what system the server is running?
ftp_systype() provides you with exactly this information.
-------------------------------------------------- ----------------------------------

// get system type
$server_os = ftp_systype($conn);

?>
-------------------------- -------------------------------------------------- ----
Regarding the switch of passive mode (PASV), PHP also provides such a function, which can turn PASV on or off (1 means on)
------------ -------------------------------------------------- ------------------

// turn PASV on
ftp_pasv($conn, 1);

?>
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Now, you already know that you Now that "where" and "who" are with you, let's start walking around in the directory - what implements this function is the ftp_chdir() function, which accepts a directory name as a parameter.
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// change directory to "public_html"
ftp_chdir($conn, "public_html");

?>
--------------------- -------------------------------------------------- --------
If you want to return to the directory you were in (parent directory), ftp_cdup() can help you realize your wish. This function can return to the previous directory.
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// go up one level in the directory tree
ftp_cdup($conn);

?>
------------------------ -------------------------------------------------- ------
You can also create or move a directory using the ftp_mkdir() and ftp_rmdir() functions; Note: If ftp_mkdir() is successfully created, it will return the name of the newly created directory.
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// make the directory "test"
ftp_mkdir($conn, "test");

// remove the directory "test"
ftp_rmdir($conn, "test");

? >
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Creating an FTP directory is usually to transfer files--- So let’s get started!

First upload the file. The ftp_put() function is well suited for this task. It requires you to specify a local file name, the uploaded file name and the type of transfer. For example: If you want to upload the file "abc.txt" and name it "xyz.txt" after uploading, the command should be like this:
----------------- -------------------------------------------------- -------------

// upload
ftp_put($conn, "xyz.txt", "abc.txt", FTP_ASCII) ;

?>
---------------------------------------- ------------------------------------------
Download file:
The function provided by PHP is ftp_get(), which also requires a file name on the server, the file name after downloading, and the transfer type as parameters. For example: the server-side file is his.zip, and you want to download it to the local machine. And named hers.zip, the command is as follows:
---------------------------------------- ------------------------------------------

// download
ftp_get($conn, "hers.zip", "his.zip", FTP_BINARY);

?>
------ -------------------------------------------------- -----------------------
PHP defines two modes as transmission modes FTP_BINARY and FTP_ASCII. Please see the above two examples for the use of these two modes. , as for its detailed explanation, this article will not go into details. Please refer to relevant books for details.




How should I list the files? (Use DIR? :) )
PHP provides two methods: one is to simply list the file name and directory, and the other is to list the file size, permissions, creation time and other information in detail.
The first one uses the ftp_nlist() function, and the second one uses ftp_rawlist(). Both functions require a directory name as a parameter, and both return the directory column as an array. Each element of the array is equivalent to the list. One line.
-------------------------------------------------- ----------------------------------

// obtain file listing
$filelist = ftp_nlist($conn, ".");

?>
---------------------- -------------------------------------------------- --------
You must want to know the size of the file! Don't worry, here is a very easy function ftp_size(), which returns the size of the file you specify, using BITES as the unit. It should be noted that if it returns "-1", it means that this is a directory. In the following examples, you will see the application of this feature.
-------------------------------------------------- ----------------------------------

// obtain file size of file "data.zip"
$filelist = ftp_size($conn, "data.zip");

?>

Now, we have contacted PHP about FTP A large number of functions, but these are just functions, which is far from our goal. To show the real power of these functions, we should build a program that can upload and download files in WEB mode---this is what we will do Made!

Before we get into the code, what I want to tell you is that this example is just to explain the use of various FTP functions of PHP. It is not perfect in many aspects, such as error analysis, etc. As far as you want to apply it to your own programs, you should make some modifications!

The program includes the following files:
index.html - Login file

actions.php - FTP code necessary for the program

include.php - Main interface of the program , which displays a file list and control buttons.

Let’s start with "index.html":
----------------------------- --------------------------------------------------

< ;tr>

Server
User
Password

-------------------------- -------------------------------------------------- --
This is a login form with a server name, username, password, and input boxes. The entered variables will be stored in the $server, $username and $password variables. After the form is submitted, actions.php is called, which will initialize the FTP connection.

Note that "hidden" is passed to action.php as a variable $action with the value CWD.


This is the source code of the action.php file:
----------------------------- -------------------------------------------------- -









//Check the data from the form, if it is not complete, an error will be reported. If you want the program to be perfect, There should be a more complete input detection function here
if (!$server
!$username
!$password)
{
echo "Incomplete data submitted!";
}
else
{
// keep reading
}

?>



- -------------------------------------------------- --------------------------


Next is the variable "actions". The program allows the following action:

"action=CWD"

Change the working directory

"action=Delete"

Delete the specified file

"action =Download"

Download the specified file

"action=Upload"

Upload the specified file

If you check the file include.php carefully, include it in it An HTML interface, you will see, consists of many forms, each pointing to a specific function. Each form contains a field (usually hidden), and when the form is submitted, the corresponding function will be executed.

For example: when "Delete" is pressed, "action=Delete" is sent to "actions.php"

In order to operate these four functions, the code in actions.php is as follows:
---------------------------------------------------------------- ----------------------------------
// action: change directory
if ($action == "CWD")
{
// Specific code
}

// action: delete file
else if ($action == "Delete")
{
// Specific code
}
// action: Download file
else if ($action == "Download")
{
// Specific code
}
// action: upload file
else if ($action == "Upload")
{
// specific code
}

?>
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The above specific code will implement the specified function and exit the loop , they all contain the following steps:

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By custom function Connect and log in to the FTP server
connect();

Change to the appropriate directory

Execute the selected function

Refresh the list to see the results of the change

Display the file list and control buttons through include("include.php")

Close the connection
--------------------- -------------------------------------------------- ---------
Note:
The following functions support multi-file operations - namely "action=Delete" and "action=Download" which are implemented using FOR loops.
The variables $cdir and $here will be updated in real time at each stage.