By Vikram Vaswani
Melonfire
November 07, 2000
We are a loyal FANS of PHP, we use it for a variety of reasons - development of WEB site, drawing, joining databases, etc. - we found that it is 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 the database, 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 can transfer files through HTTP and FTP connections. There will also be some simple program code, follow me!
First of all, you should know that PHP transfers files through HTTP and FTP connections. Uploading files via HTTP has appeared as early as PHP3. Now, the new FTP function has appeared in the new PHP version!
Before you start, you need to be sure that your PHP supports FTP, you can check it out by following the following code:
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<?
phpinfo();
?>
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Check the output results and there is a "Additional Modules" area, which lists the modules supported by your PHP; if you don't find FTP modules, you'd better reinstall PHP and add FTP support!
Let’s first take a look at how a typical FTP task is completed!
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$ ftp
Connected to
220 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
226 Transfer complete.
ftp> bin
200 Type set to I.
ftp> get
local: remote:
200 PORT command successful.
150 Opening BINARY mode data connection for (2941465 bytes).
226 Transfer complete.
ftp> bye
221 Goodbye.
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You can see that the process is obviously divided into several segments: join (establishing a connection with the FTP server), verification (to determine whether the user has the authority to enter the system), transmission (including column directories, uploading or downloading files here), and canceling the connection.
Steps to Use PHP to FTP
To establish a PHP FTP connection, you must follow the following basic steps: Open a join - issue authentication information - use PHP functions to manipulate directories and transfer files.
The following specific implementations:
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<?
// Join FTP server
$conn = ftp_connect("");
// Log in using username and password
ftp_login($conn, "john", "doe");
// Get the remote system type
ftp_systype($conn);
// List the file
$filelist = ftp_nlist($conn, ".");
// Download the file
ftp_get($conn, "", "", FTP_BINARY);
// Close the connection
ftp_quit($conn);
?>
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Let's go step by step:
In order to initially encrypt an FTP connection, PHP provides the function ftp_connect(), which uses the host name and port as parameters. In the example above, the host name is ""; 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() passes back a handle; this handle will be used by the FTP function used later.
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<?
// connect to FTP server
$conn = ftp_connect("");
?>
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Once the join is established, use ftp_login() to send a user name and user password. You can see that this function ftp_login() uses the handle from the ftp_connect() function to determine that the user name and password can be submitted to the correct server.
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<?
// log in with username and password
ftp_login($conn, "john", "doe");
?>
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At this time, you can do what you want to do, and in the next part:
After doing what you want, remember to use the ftp_quit() function to close your FTP connection
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<?
// close connection
ftp_quit($conn);
?>
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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);
?>
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What if you need to know what system is running on the server side?
ftp_systeme() just provides you with information about this.
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<?
// get system type
$server_os = ftp_systype($conn);
?>
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Regarding the switch of passive mode (PASV), PHP also provides a function that can turn PASV on or off (1 means on)
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<?
// turn PASV on
ftp_pasv($conn, 1);
?>
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Now that you already know where you are with you, we're going to stroll through the directory -- the ftp_chdir() function that implements this function, which accepts a directory name as a parameter.
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<?
// change directory to "public_html"
ftp_chdir($conn, "public_html");
?>
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If you want to go back to the directory you were in (parent directory), ftp_cdup() can help you realize your wish, and this function can go back to the previous level directory.
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<?
// go up one level in the directory tree
ftp_cdup($conn);
?>
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You can also create or move a directory, which requires the use of the ftp_mkdir() and ftp_rmdir() functions; note: if ftp_mkdir() is successfully established, the newly created directory name will be returned.
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<?
// make the directory "test"
ftp_mkdir($conn, "test");
// remove the directory "test"
ftp_rmdir($conn, "test");
?>
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Creating an FTP directory is usually to transfer files--- So let's get started!
First, upload the file. The ftp_put() function is very competent for this responsibility. It requires you to specify a local file name, uploaded file name and transfer type. For example: If you want to upload the file "" and then name it "" after uploading, the command should be like this:
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<?
// upload
ftp_put($conn, "", "", FTP_ASCII);
?>
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Download the file:
The function provided by PHP is ftp_get(), which also requires a file name on the server, the downloaded file name, and the transmission type as parameters. For example: the server side file is, you want to download it to the local machine and name it, the command is as follows:
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<?
// download
ftp_get($conn, "", "", FTP_BINARY);
?>
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PHP defines two modes as transmission modes FTP_BINARY and FTP_ASCII. Please read the above two examples of the use of these two modes. As for their detailed explanation, I won’t say much about this article. Please refer to the 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 a row of the list.
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<?
// obtain file listing
$filelist = ftp_nlist($conn, ".");
?>
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You must want to know the file size! Don't worry, here is a very easy function ftp_size(), which returns the size of the file you specified, using BITES as the unit. It should be noted that if it returns "-1", it means that this is a directory, and in the following examples you will see the application of this feature.
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<?
// obtain file size of file ""
$filelist = ftp_size($conn, "");
?>
Now, we have come into contact with PHP's large number of functions about FTP, but this is just a function, which is far from our goal. To show the true power of these functions, we should build a program that can be uploaded in WEB mode and downloaded files--this is what we are going to do!
Before we enter the code, what I want to tell you is that this example is just to explain to you the use of various FTP functions in PHP, and many aspects are not perfect, such as error analysis, etc. As for what you want to apply to your own program, you should make some modifications!
The program includes the following files:
- Login file
- FTP code required for the program
- The main interface of the program, which displays the file list and control buttons.
Let's start with "":
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<table border=0 align=center>
<form action="" method=post>
<input type=hidden name=action value=CWD>
<tr>
<td>
Server
</td>
<td>
<input type=text name=server>
</td>
</tr>
<tr>
<td>
User
</td>
<td>
<input type=text name=username>
</td>
</tr>
<tr>
<td>
Password
</td>
<td>
<input type=password name=password>
</td>
</tr>
<tr>
<td colspan=2 align=center>
<input type="submit" value="Beam Me Up, Scotty!">
</td>
</tr>
</form>
</table>
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This is a login form with a server name, username, password, and input box. The input variable will be stored in the $server, $username and $password variables. After the form is submitted, it will initialize the FTP connection.
Note that "hidden" is passed to a variable $action with a value of CWD.
This is the source code of the file:
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<html>
<head>
<basefont face=Arial>
</head>
<body>
<!-- the interface will be inserted into this page -->
<?
//Check the data sent from the form. If the program is not complete, an error will be reported. If you want to improve the program, there should be a more complete input detection function here.
if (!$server
!$username
!$password)
{
echo "The submission data is incomplete!";
}
else
{
// keep reading
}
?>
</body>
</html>
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Next is the variable "actions". The program allows the following actions:
"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 double-check the file and include an HTML interface inside, you will see that it includes many forms, each pointing to a specific function, each form containing a field (usually hidden), and when the form is submitted, the corresponding function will be executed.
For example: Press "Delete", "action=Delete" will be transmitted to ""
In order to operate these four functions, the code in this article is as follows:
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<?
// action: Change directory
if ($action == "CWD")
{
// Specific code
}
// action: delete file
else if ($action == "Delete")
{
// Specific code
}
// action: Download the 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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Join and log in to the FTP server through customized functions
connect();
Turn to the appropriate catalog
Perform the selected function
Refresh the list to see the changes
Display file list and control buttons via include("").
Close the connection
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Notice:
The following functions support multi-file operations - i.e. "action=Delete" and "action=Download" are implemented using FOR loops.
The variables $cdir and $here will be updated in real time at each stage.