If you have multiple PHP versions installed, you may be able to specify for which installation you'd like to build by using the --with-php-config option during configuration.
--with-php-config=[Insert path to proper php-config here]
For example (my case):
Compiling shared PECL extensions with phpize
Sometimes, using the pecl installer is not an option. This could be because you're behind a firewall, or it could be because the extension you want to install is not available as a PECL compatible package, such as unreleased extensions from SVN. If you need to build such an extension, you can use the lower-level build tools to perform the build manually.
The phpize command is used to prepare the build environment for a PHP extension. In the following sample, the sources for an extension are in a directory named extname:
$ cd extname $ phpize $ ./configure $ make # make install
A successful install will have created extname.so and put it into the PHP extensions directory. You'll need to and adjust php.ini and add an extension=extname.so line before you can use the extension.
If the system is missing the phpize command, and precompiled packages (like RPM's) are used, be sure to also install the appropriate devel version of the PHP package as they often include the phpize command along with the appropriate header files to build PHP and its extensions.
Execute phpize --help to display additional usage information.
When compiling an extension for a stack which is 64 bits (for example) and your compiler is configured to compile in 32 bits, you can manually compile your extensions using C flags before your configure.
Example: my system compiler is 32 bits and my stack is 64 bits. To compile my xdebug:
# CFLAGS=-m64 CPPFLAGS=-m64 CCASFLAGS=-m64 ./configure --enable-xdebug
# file modules/xdebug.so
modules/xdebug.so: ELF 64-bit LSB dynamic lib AMD64 Version 1, dynamically linked, not stripped, no debugging information available
When you have multiple installations of PHP, running phpize from a specific installation will not force the module to be compiled with that installation's include files.
In my case, I had a standard PHP distribution installed, and am evaluating Zend Core / Zend Platform, which installed it's own Apache & PHP in a /usr/local/Zend/.. install path. It was missing the json.so module, so I had to compile my own.
Running Zend Core's phpize, the output indicates that configuration for that module will occur. But when running ./configure, the standard installation's include files are used. The result json.so being compiled against the wrong PHP would not load when Zend Core's php initializes.
The only way I could see to correct the situation was to temporarily change the standard PHP include path to point to the Zend Core's include files. In my case, I made a backup copy of /usr/include/php5 and did a "ln -s /usr/local/Zend/Core/include/php/ /usr/include/php5".
In some situations (e.g. on a cPanel server), the built extension will not be placed into the correct extensions directory by the make install process. Use your phpinfo() output to determine what the correct extension_dir path is and move the generated .so file into that directory. The extension=extname.so line in php.ini will then find the extension file correctly.
Minimizing harm on upgrading extensions on busy server.
I upgraded (phpize,make... way) APC-extension on quite busy server and found out that Apache segfaults if i just restart it gracefully with the new extension in place. I found a way around this, so that the users of the server only see small slow down of the services.
1. Comment out extension loading (old extension) in php.ini (or separate .ini-file).
2. Restart Apache gracefully (now system runs without extension).
3. Replace old extension with new version (can be done already before first restart) and edit .ini again to include extension.
4. Restart Apache gracefully again (new extension loads).
Of course this only works for extensions which your php-application can live without for a short period of time. ;-)