sudo apt-get install php5-intl
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.
Informazioni per l'installazione di questa estensione PECL possono essere trovate nel capitolo del manuale intitolato Installazione delle estensioni PECL. Informazioni aggiuntive come nuove release, download, file sorgenti, informazioni del manutentore e un CHANGELOG possono essere trovate qui: » http://pecl.php.net/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
environment variable so that dynamic linker can find it:
Otherwise, if PHP and ICU are installed to their default locations, then the additional options to `configure' are not needed.
I'm running on Mac OS X using a MacPorts install. According to this page, my vanilla version of PHP 5.3.5 from MacPorts should include the intl functions by default. As far as I can see from phpinfo(), the MacPorts version did not disable it. However, the functions aren't visible and don't work.
It seems to require an additional:
sudo port install php5-intl
After which everything bursts into life.
You need to install the library.
yum install libicu-devel
Will get it working with "pecl install intl"
On Fedora 18 "pecl install intl" wasn't working after "yum -y install icu" so I had to run "yum -y install php-intl" instead