Using PHP with a Web-Hosting Provider

If you already have an account with a web-hosting provider, you probably have access to a PHP-enabled server. These days, it is the odd web-hosting provider that doesn’t have PHP support. Usually, hosting providers configure their servers so that files whose names end in .php are treated as PHP programs. To see whether your hosted website supports PHP, first save the file in Example A-1 on your server as phptest.php.

<?php print "PHP enabled"; ?>

Load the file in your browser by visiting the URL for your site (e.g., http://www.example.com/phptest.php). If you see just the message PHP enabled, then your website host supports PHP. If you see the entire contents of the page (<?php print "PHP enabled"; ?>), then your hosting provider probably doesn’t support PHP. Check with them, however, to make sure that they haven’t turned on PHP for a different file extension or made some other nonstandard configuration choice.

Installing the PHP Engine

Installing the PHP engine on your own computer is a good idea if you don’t have an account with a hosting provider, or you just want to experiment with PHP without exposing your programs to the entire Internet. If you’re not using a hosting provider and want to install the PHP engine on your own computer, follow the instructions in this section. After you’ve installed the engine, you’ll be able to run your own PHP programs.

Installing the PHP engine is a matter of downloading some files and putting them in the right places on your computer. You may also need to configure your web server so that it knows about PHP. This section contains instructions on how to do this for computers running Linux and OS X, and also includes some references for how to install PHP on Windows. If you get stuck, check out the php.net installation FAQ.

ruby -e "$(curl -fsSL 
https://raw.githubusercontent.com/Homebrew/install/master/install)"

brew tap homebrew/dupes
brew tap homebrew/versions
brew tap homebrew/homebrew-php

gunzip php-7.0.5.tar.gz
tar xvf php-7.0.5.tar

Modifying PHP Configuration Directives

Earlier chapters in the book mention various PHP configuration directives. These are settings that affect the behavior of the PHP engine, such as how errors are reported, where the PHP engine looks for included files and extensions, and much more.

Read this section when you encounter a configuration directive you want to alter or are curious about how you can tweak the PHP engine’s settings (whether you are using PHP on your own computer or with a hosting provider). For example, changing the output_buffering directive (as discussed in “Why setcookie() and session_start() Want to Be at the Top of the Page”) makes your life much easier if you are working with cookies and sessions.

The values of configuration directives can be changed in a few places: in the PHP engine’s php.ini configuration file, in Apache’s httpd.conf or .htaccess configuration files, and in your PHP programs. Not all configuration directives can be changed in all places. If you can edit your php.ini or httpd.conf file, it’s easiest to set PHP configuration directives there. But if you can’t change those files because of server permissions, then you can still change some settings in your PHP programs.

If your web server talks to the PHP engine using CGI or FastCGI, you can also set configuration directives in .user.ini files. In PHP 5.3.0 and later, the PHP engine looks for a file called .user.ini in the same directory as the PHP program it’s running. If the PHP program is inside the web server’s document root, the PHP engine also looks in the program’s parent directory, and that directory’s parent, and so on, up to the document root. The syntax for .user.ini files is the same as for the main php.ini file.

The php.ini file holds systemwide configuration for the PHP engine. When the web server process starts up, the PHP engine reads the php.ini file and adjusts its configuration accordingly. To find the location of your system’s php.ini file, examine the output from the phpinfo() function. This function prints a report of the PHP engine’s configuration. The tiny program in Example A-2 produces a page that looks like the one in Figure A-1.

<?php phpinfo(); ?>

In Figure A-1, the sixth line (Configuration File (php.ini) Path) shows that the php.ini file is located at /php7/etc/php.ini. Your php.ini file may be in a different place.

Figure A-1. Output of phpinfo()

In the php.ini file, lines that begin with a semicolon (;) are comments. Lines that set values for configuration directives look like those shown in Example A-3.

; How to specify directories on Unix: forward slash for a separator
; and a colon between the directory names
include_path = ".:/usr/local/lib/php/includes"

; How to specify directories on Windows: backslash for a separator
; and a semicolon between the directory names
; Windows: "\path1;\path2"
include_path = ".;c:\php\includes"

; Report all errors except notices
error_reporting = E_ALL & ~E_NOTICE

; Record errors in the error log
log_errors = On

; An uploaded file can't be more than 2 megabytes
upload_max_filesize = 2M

; Sessions expire after 1440 seconds
session.gc_maxlifetime = 1440

The error_reporting configuration directive is set by combining built-in constants with logical operators. For example, the line error_reporting = E_ALL & ~E_NOTICE sets error_reporting to E_ALL but not E_NOTICE. The operators you can use are & (“and”), | (“either ... or”), and ~ (“not”). So, to the PHP engine, E_ALL & ~E_NOTICE means E_ALL and not E_NOTICE. You may find it easier to read “and not” as “but not,” as in E_ALL but not E_NOTICE. The setting E_ALL | E_NOTICE means either E_ALL or E_NOTICE.

When setting a configuration directive whose value is a number (such as upload_max_filesize), you can use M (for megabyte) or K (for kilobyte) at the end of the number to multiply by 1,048,576 or 1,024. Setting upload_max_filesize=2M is the same as setting upload_max_filesize=2097152. There are 1,048,576 bytes in a megabyte, and 2,097,152 = 2 * 1,048,576.

To change a configuration directive in Apache’s httpd.conf or .htaccess file, you must use a slightly different syntax, shown in Example A-4.

; How to specify directories on Unix: forward slash for a separator
; and a colon between the directory names
php_value include_path ".:/usr/local/lib/php/includes"

; How to specify directories on Windows: backslash for a separator
; and a semicolon between the directory names
; Windows: "\path1;\path2"
php_value include_path ".;c:\php\includes"

; Report all errors but notices
php_value error_reporting "E_ALL & ~E_NOTICE"

; Record errors in the error log
php_flag log_errors On

; An uploaded file can't be more than 2 megabytes
php_value upload_max_filesize 2M

; Sessions expire after 1440 seconds
php_value session.gc_maxlifetime 1440

The php_flag and php_value words in Example A-4 tell Apache that the rest of the line is a PHP configuration directive. After php_flag, put the name of the configuration directive and then On or Off. After php_value, put the name of the directive and then its value. If the value has spaces in it (such as E_ALL & ~E_NOTICE), you must put it in quotes. There is no equals sign between the name of the configuration directive and the value.

To change a configuration directive from within a PHP program, use the ini_set() function. Example A-5 sets error_reporting from within a PHP program.

ini_set('error_reporting',E_ALL & ~E_NOTICE);

The first argument to ini_set() is the name of the configuration directive to set. The second argument is the value to which you want to set the configuration directive. For error_reporting, that value is the same logical expression as you’d put in php.ini. For configuration directives whose values are strings or integers, pass the string or integer to ini_set(). For configuration directives whose values are On or Off, pass 1 (for On) or 0 (for Off) to ini_set().

To find the value of a configuration directive from within a program, use ini_get( ). Pass it the name of the configuration directive, and it returns the value. This is useful for adding a directory to the include_path, as shown in Example A-6.

// These lines add /home/ireneo/php to the end of the include_path
$include_path = ini_get('include_path');
ini_set('include_path',$include_path . ':/home/ireneo/php');

As mentioned earlier, not all configuration directives can be set in all places. There are some configuration directives that cannot be set from within your PHP programs. These are directives that the PHP engine must know about before it starts reading your program, such as output_buffering. The output_buffering directive makes a change to the engine’s behavior that must be active before the engine gets a look at your program, so you can’t set output_buffering with ini_set(). In addition, some configuration directives are prohibited from being set in Apache .htaccess files and some from being set in the Apache httpd.conf file. All configuration directives can be set in the php.ini file.

The PHP Manual has a big list of all the configuration directives and the contexts in which they can be changed. Some useful configuration directives to know about are listed in Table A-1.

Appendix Summary

This appendix covered:

• Using PHP with a web-hosting provider
• Installing the PHP engine on OS X, Linux, or Windows
• Using phpinfo() to see the PHP engine’s configuration
• Understanding the structure of the php.ini configuration file
• Configuring the PHP engine in the httpd.conf configuration file
• Reading and writing configuration directive values with ini_get() and ini_set()
• Using common configuration directives