centos5.3,centos5.4安装webmin默认的是 mysql 5.0,php5.1 我需要升级到mysql5.1和php5.2(禁止php5.3)，怎么办？
给yum安装rpmforge：
http://wiki.centos.org/AdditionalResources/Repositories/RPMForge
yum list mysql php 发现都是最新版本了，看来标准的yum源没有更新
wget http://download.fedora.redhat.com/pub/epel/5/i386/epel-release-5-3.noarch.rpm
wget http://rpms.famillecollet.com/el5.i386/remi-release-5-7.el5.remi.noarch.rpm
rpm -Uvh remi-release-5-7.el5.remi.noarch.rpm epel-release-5-3.noarch.rpm
yum --enablerepo=remi list mysql
发现可以升级到 mysql 5.1.44-1.el5.remi
yum --enablerepo=remi update mysql
发现需要把php也一并升级到 5.3，
而zend optimizer 目前不支持 Php5.3，于是需要禁止升级php5.3
vi /etc/yum.conf
最后一行增加
exclude=php*5.3*
然后再yum --enablerepo=remi update mysql，就看不到php的升级了
搞定：
[root@www.ctohome.com backup]# php -v 还是旧的5.1.6
PHP 5.1.6 (cli) (built: Jan 13 2010 17:13:05)
Copyright (c) 1997-2006 The PHP Group
Zend Engine v2.1.0, Copyright (c) 1998-2006 Zend Technologies
with Zend Extension Manager v1.2.2, Copyright (c) 2003-2007, by Zend Technologies
with Zend Optimizer v3.3.3, Copyright (c) 1998-2007, by Zend Technologies
[root@www.ctohome.com backup]# mysql -V 升级到5.1.44了
mysql Ver 14.14 Distrib 5.1.44, for redhat-linux-gnu (i686) using readline 5.1
升級mysql 5.1.41-1之後,請執行下列動作:
(1)將原有的/etc/my.cnf備份,將/etc/my.cnf.rpmnew改 為my.cnf
(2)升級table
mysql_upgrade -p
(3)自動修復table
mysqlcheck --all-databases --check-upgrade --auto-repair -p
找到一个yum源，有php5.2，方法如下：
http://www.webtatic.com/blog/2009/06/php-530-on-centos-5/
rpm --import http://repo.webtatic.com/yum/RPM-GPG-KEY-webtatic-andy
wget -P /etc/yum.repos.d/ http://repo.webtatic.com/yum/webtatic.repo
yum --enablerepo=webtatic list php
发现有php5.2 和 php5.3可以升级，
OK，我们vi /etc/yum.conf 禁止升级php5.3
vi /etc/yum.conf
最后一行增加
exclude=php*5.3*
或者：
yum --enablerepo=webtatic --exclude=php*5.3* list php
yum --enablerepo=webtatic --exclude=php*5.3* update -y php
[root@www.ctohome.com backup]# php -v 升级到5.2.12了，收工！
PHP 5.2.12 (cli) (built: Dec 17 2009 19:40:56)
Copyright (c) 1997-2009 The PHP Group
Zend Engine v2.2.0, Copyright (c) 1998-2009 Zend Technologies
with Zend Extension Manager v1.2.2, Copyright (c) 2003-2007, by Zend Technologies
with Zend Optimizer v3.3.3, Copyright (c) 1998-2007, by Zend Technologies
安装完成后需要安装php-devel和httpd-devel两个组件
yum --enablerepo=webtatic --exclude=php*5.3* install php-devel
yum --enablerepo=webtatic --exclude=php*5.3* install httpd-devel
否则，以后会出错。
yum-allowdowngrade 可以降级的插件：
allow downgrade for yum:
yum install yum-allowdowngrade
Add a line to yum.conf:
showdupesfromrepos=1
After that list all php packages:
yum list php
If php 5.2.8 is available, remove new one:
yum remove php
and install an old one:
yum --allow-downgrade install php-5.2.8