PHP

PHP is a general-purpose server-side scripting language to produce dynamic web pages. It began development in 1993 and was first officially released in 1995. By the turn of the millennium, PHP began to displace Perl as the preferred "P" in the LAMP stack before being challenged in turn by Python. Even so, PHP remains a popular server-side scripting language for dynamic websites and web applications, perhaps in no small part due to the popularity of the WordPress blogging platform.

Installation

USE flags

The most important USE flags of the PHP package, the SAPI (Server API) USE flags, are apache2, cgi, and fpm. Alongside these flags, there is an elaborate list of flags to enable various features of the PHP interpreter:

The ebuild installs a modified "production" version of php.ini that has tighter security settings and default paths adjusted for Gentoo systems. Both upstream "production" and "development" php.ini files are installed to /usr/share/doc/php-*.

Extensions

To install extensions, first decide which versions of PHP to compile the extensions for. This is done by setting the PHP_TARGETS variable:

*/*PHP_TARGETS:php8-2

More than one version can be defined; just add in the additional versions separated by a space. Note that the php slot is named "8.2" and the corresponding PHP_TARGETS value is php8-2. This is due to current restrictions on USE names.

Emerge

After making the above USE flag configurations it is necessary to update the system so the changes take effect:

Running multiple versions of PHP

One of the great advantages of using Gentoo for PHP development is the version slotting. It is very simple to swap between multiple versions of PHP as well as run multiple versions simultaneously. This is all done with the eselect command provided by the app-eselect/eselect-php package which should get emerged in automatically by installing PHP.

For example, selecting different versions of PHP can allow a system to run PHP 7.0 for the cli SAPI but PHP 5.6 for the system's web server. It also allows system administrators or application developers to quickly test an application on different versions of PHP.

To list the available versions for the cli SAPI module use the following syntax:

 [1] php5.5 
 [2] php5.6 * 
 [3] php7.0

The * (asterisk) marks current active version for the selected module. To check the other SAPIs simply replace cli with fpm,cgi or apache2 modules.

To swap versions, use:

The number 3 in this example corresponds to the number in the output of the list sub-command used above. PHP version 7.0 is now used for the command-line:

PHP 7.0.10-pl0-gentoo (cli) (built: Aug 23 2016 12:38:44) ( NTS )

Configuration

The PHP configuration is at /etc/php, which contains one subdirectory for each Server API (SAPI) and for each PHP version. For instance, configuration files for the PHP-5.6 apache2 SAPI are installed in /etc/php/apache2-php5.6.

Web servers

To use PHP in a server-side fashion, a web server needs to be installed and configured to use PHP. A number of popular web servers are briefly touched upon next.

Nginx

Simply emerge nginx to install it:

Once Nginx has been installed, modify the server section of /etc/nginx/nginx.conf to look something like this:

server {
 listen 127.0.0.1;
 server_name localhost;
 
 access_log /var/log/nginx/localhost.access_log main;
 error_log /var/log/nginx/localhost.error_log info;
 
 root /var/www/localhost/htdocs;
 
 location ~ \.php$ {
 try_files $uri $uri/ =404;
 fastcgi_split_path_info ^(.+\.php)(/.+)$;
 fastcgi_pass 127.0.0.1:9000;
 include fastcgi.conf;
 }
 }

Now start the related services to have a working site. The php-fpm init script starts the PHP FastCGI Process Manager. FastCGI allows web servers to offload the PHP calculations to this process manager.

When running OpenRC as the service manager:

For systemd:

lighttpd

Make sure that lighttpd has the php USE flag is disabled:

www-servers/lighttpd -php

Lighttpd ships with a default FastCGI config file, but unfortunately, it is written to work with the old PHP FCGI SAPI only, instead of a general FCGI setup. Since the php USE flag has been disabled, it will not be included, and rightly so. However it does provide a good foundation for a configuration file that can be used with FPM.

Edit /etc/lighttpd/mod_fastcgi.conf to look something like this:

server.modules+=("mod_fastcgi")
fastcgi.server=(".php"=>
("localhost"=>
(
"host"=>"127.0.0.1",
"port"=>"9000"
)
)
)

Note the host and port parts.

Since Gentoo ships with a working php-fpm.ini file, located in /etc/php/fpm-php5/php-fpm.ini, and init script, starting the services is all that is needed:

Apache (mod_php)

To configure Apache to load the PHP5 module (mod_php), add -D PHP to APACHE2_OPTS variable in /etc/conf.d/apache2. Users might remember that previously, the PHP version had to be added as well (like -D PHP5). However, since app-eselect/eselect-php version 0.8.1, the variable is changed to just -D PHP to allow future major versions to be easily integrated.

## (settings for PHP5 and above)
APACHE2_OPTS="-D PHP"

Make sure that PHP is built with the apache2 USE flag.

If for some reason the system is missing the PHP module integration file /etc/apache2/modules.d/70_mod_php.conf, currently provided by app-eselect/eselect-php when installed with apache2 USE flag set, manually insert it. Its current content is displayed below.

<IfDefinePHP>
# The mod_php.so symlink is controlled by
# eselect-php. However, the module name changed from
# php5_module to php7_module so we can't blindly load whatever
# is there. Instead we let eselect-php manage a small
# configuration file that loads the appropriate module.
Include"/var/lib/eselect-php/mod_php.conf"

# Tell apache that mod_php should handle PHP files.
#
# NOTE: Avoiding AddHandler/AddType for security (bug
# #538822). Please read the related news item!
<FilesMatch"\.(php|php[57]|phtml)$">
SetHandlerapplication/x-httpd-php
</FilesMatch>

# PHP source files which are meant to be displayed as
# syntax-highlighted source code.
<FilesMatch"\.phps$">
SetHandlerapplication/x-httpd-php-source
</FilesMatch>

DirectoryIndexindex.phpindex.phtml
</IfDefine>

Although multiple PHP versions can be installed on a system, Apache can only use a single PHP version with mod_php. Support for multiple PHP versions on Apache is available using fpm. The eselect php command is used to switch between active mod PHP versions.

To change the version of PHP handled by Apache, first list the available versions for the apache2 Server Application Programming Interface (SAPI):

 [1] php5.3
 [2] php5.4 *
 [3] php5.5

Change it to the version of choice:

Substitute N in the example above to the requested number in the output of eselect php list apache2 as displayed earlier on.

To verify the PHP module works, create a test page:

<html>
 <body>
<?php phpinfo(); ?>
 </body>
</html>

Now, suppress or rename /var/www/localhost/htdocs/index.html and open the test page: http://localhost/

A table describing the PHP settings should be visible.

Apache (fcgid)

See enabling PHP through fcgid in the Apache article.

Apache (mod_proxy_fcgi)

See enabling PHP-FPM through mod_proxy_fcgi in Apache 2.4.

See also

• Upgrading to PHP 5.6, guide to upgrade older installations to 5.6
• Upgrading to PHP 7.1, guide to upgrade older installations to 7.1
• Enabling PHP support in the Apache article
• Perl — a general purpose interpreted programming language with a powerful regular expression engine.
• Python — an extremely popular cross-platform object oriented programming language.

External resources

• Running Multiple Versions of PHP Using Apache on Gentoo

• PHP