参考: CentOS 5 で DAG(rpmforge) の yum repository 追加 – Enjoi Blog

epel, remi, rpmforgeをレポジトリに追加してあげればいい。

レポジトリの準備

wget http://rpms.famillecollet.com/el5.i386/remi-release-5-4.el5.remi.noarch.rpm
wget http://download.fedora.redhat.com/pub/epel/5/i386/epel-release-5-2.noarch.rpm
wget http://dag.wieers.com/rpm/packages/rpmforge-release/rpmforge-release-0.3.6-1.el5.rf.i386.rpm
rpm -ivh remi-release-5-4.el5.remi.noarch.rpm epel-release-5-2.noarch.rpm rpmforge-release-0.3.6-1.el5.rf.i3

実際のアップグレード操作

yum --enablerepo=remi,rpmforge update php*

確認

[root@sabato tmp]# php -v
PHP 5.2.6 (cli) (built: May  7 2008 00:50:43)
Copyright (c) 1997-2008 The PHP Group
Zend Engine v2.2.0, Copyright (c) 1998-2008 Zend Technologies