&reftitle.install; This extension may be installed using the bundled version as of PHP 5.3.0, or as a PECL extension as of PHP 5.2.0. In other words, there are two methods to install the intl extension. &pecl.info; &url.pecl.package;intl. Alternatively, --enable-intl will enable the bundled version while compiling PHP. If your ICU is installed to a non-standard directory then you might want to specify its location in LD_LIBRARY_PATH environment variable so that dynamic linker can find it: $ export LD_LIBRARY_PATH=/opt/icu/lib Otherwise, if PHP and ICU are installed to their default locations, then the additional options to `configure' are not needed.