OS X users editing in TextEdit will need to make sure their TextEdit preferences are set to allow plain text files. Under the TextEdit pull-down menu, choose PREFERENCES, then under NEW DOCUMENT ATTRIBUTES in the window that pops up, click PLAIN TEXT.
Then, in the section of that same window called "saving," DESELECT "append .txt extension to plain text files." This will allow you to save your files with a .php extension.
Then close the PREFERENCES window. You're good to go.
Your first PHP-enabled page
Create a file named hello.php and put it in your web server's root directory (DOCUMENT_ROOT) with the following content:
Example #1 Our first PHP script: hello.php
<?php echo '<p>Hello World</p>'; ?>
Use your browser to access the file with your web server's URL, ending with the /hello.php file reference. When developing locally this URL will be something like http://localhost/hello.php or http://127.0.0.1/hello.php but this depends on the web server's configuration. If everything is configured correctly, this file will be parsed by PHP and the following output will be sent to your browser:
<html> <head> <title>PHP Test</title> </head> <body> <p>Hello World</p> </body> </html>
This program is extremely simple and you really did not need to use PHP to create a page like this. All it does is display: Hello World using the PHP echo statement. Note that the file does not need to be executable or special in any way. The server finds out that this file needs to be interpreted by PHP because you used the ".php" extension, which the server is configured to pass on to PHP. Think of this as a normal HTML file which happens to have a set of special tags available to you that do a lot of interesting things.
If you tried this example and it did not output anything, it prompted for download, or you see the whole file as text, chances are that the server you are on does not have PHP enabled, or is not configured properly. Ask your administrator to enable it for you using the Installation chapter of the manual. If you are developing locally, also read the installation chapter to make sure everything is configured properly. Make sure that you access the file via http with the server providing you the output. If you just call up the file from your file system, then it will not be parsed by PHP. If the problems persist anyway, do not hesitate to use one of the many » PHP support options.
The point of the example is to show the special PHP tag format. In this example we used <?php to indicate the start of a PHP tag. Then we put the PHP statement and left PHP mode by adding the closing tag, ?>. You may jump in and out of PHP mode in an HTML file like this anywhere you want. For more details, read the manual section on the basic PHP syntax.
Note: A Note on Line Feeds
Line feeds have little meaning in HTML, however it is still a good idea to make your HTML look nice and clean by putting line feeds in. A linefeed that follows immediately after a closing ?> will be removed by PHP. This can be extremely useful when you are putting in many blocks of PHP or include files containing PHP that aren't supposed to output anything. At the same time it can be a bit confusing. You can put a space after the closing ?> to force a space and a line feed to be output, or you can put an explicit line feed in the last echo/print from within your PHP block.
Note: A Note on Text Editors
There are many text editors and Integrated Development Environments (IDEs) that you can use to create, edit and manage PHP files. A partial list of these tools is maintained at » PHP Editors List. If you wish to recommend an editor, please visit the above page and ask the page maintainer to add the editor to the list. Having an editor with syntax highlighting can be helpful.
Note: A Note on Word Processors
Word processors such as StarOffice Writer, Microsoft Word and Abiword are not optimal for editing PHP files. If you wish to use one for this test script, you must ensure that you save the file as plain text or PHP will not be able to read and execute the script.
Note: A Note on Windows Notepad
If you are writing your PHP scripts using Windows Notepad, you will need to ensure that your files are saved with the .php extension. (Notepad adds a .txt extension to files automatically unless you take one of the following steps to prevent it.) When you save the file and are prompted to provide a name for the file, place the filename in quotes (i.e. "hello.php"). Alternatively, you can click on the 'Text Documents' drop-down menu in the 'Save' dialog box and change the setting to "All Files". You can then enter your filename without quotes.
Now that you have successfully created a working PHP script, it is time to create the most famous PHP script! Make a call to the phpinfo() function and you will see a lot of useful information about your system and setup such as available predefined variables, loaded PHP modules, and configuration settings. Take some time and review this important information.
Example #2 Get system information from PHP
<?php phpinfo(); ?>
Note on permissions of php files: You don't have to use 'chmod 0755' under UNIX or Linux; the permissions need not be set to executable. Again, this is more like a html file than a cgi script. The only mandatory requirement is that the web server process has read access to the php file(s). With many Linux systems, it is popular for Apache to run under the 'apache' account. Given that HTML and other web files, like php, are often owned by user 'root' and group 'web' (or another similar group name), acceptable permissions might be those achieved with 'chmod 664' or 'chmod 644'. The web server process, running under the 'apache' account, will inherit read only permissions. The 'apache' account is not root and is not a member of the 'web' group, so the "other" portion of the permissions (the last "4") applies.
Well, but PHP file ownership is important when server has safe_mode enabled - HTTP server checks it, uses it to set UID of process which executes it, or may even refuse to execute such a file - e.g. if one user is owner of main PHP file, and the main file includes another, owned by other user, this is considered to be security violation (quite reasonably).
document_root variable is located in your web server configuration file
If you save your code as UTF-8, make sure that the BOM (EF BB BF) is not present as the first 3 bytes of the file otherwise it may interfere with the code if the PHP need to be run before any output (e.g. header()).
On Windows, if file extensions can be hidden, you may not SEE that you have accidently saved a file as 'Text Documents' (and that the browser has added '.txt' to the end of your 'page.html', resulting in 'page.html.txt'.) You still see only 'page.html' even though it's really 'page.html.txt'. Also, if you try to rename it, it won't work because it's not overwriting the '.txt' part and not changing the filetype.
By the way, the hiding of file extensions is ALSO a way malicious crackers get you to click on an executable virus, fooling you into thinking it's an innocent document. You should always be able to view the extensions of all files on your system.
To view all extensions, open Windows Explorer. Click the 'Tools' menu, then 'Folder Options'. In the dialog box that appears, click the 'View' tab. In the 'Advanced Settings Box', scroll down to 'Hide extensions for known file types' and click the checkbox next to it to REMOVE THE CHECKMARK. Click the 'Apply to All Folders' button near the top of the dialog. This may or may not take a few minutes. Then click the 'OK' button to close the dialog.
Now, if something accidentally gets saved as the wrong filetype, resulting in another file extension automatically appended to the one you typed, you will see it and be able to rename it.
Of course, a badly-named file can be renamed simply by using 'Save As' and saving it as the proper filetype, but if you can't see the file extension, you may not know that is the problem. Also, renaming is easier than opening, resaving as a new filetype, and then deleting the old version!