New Server has come and again I must downgrade php version to 5.2 due to some problem on web application. I use same method I use for Ubuntu 10.04 for Ubuntu 10.10 x86.
Let start
Download required files for PHP 5.2 from Ubuntu Karmic repository
#cd /etc/apt/sources.list.d
#wget http://randyfay.com/sites/default/files/karmic_0.list
# cd /etc/apt/preferences.d/
#wget http://randyfay.com/sites/default/files/php_1.
# mv php_1. php
Find out installed PHP version
# php -v
PHP 5.3.3-1ubuntu9.1 with Suhosin-Patch (cli) (built: Oct 15 2010 14:00:18)
Copyright (c) 1997-2009 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies
## dpkg –get-selections | grep php
libapache2-mod-php5Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â install
php-db                                         install
php-pear                                       install
php5Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â install
php5-cli                                       install
php5-common                                    install
php5-gd                                        install
php5-mcrypt                                    install
php5-mysql                                     install
php5-xsl                                       install
Delete those PHP with apt-get remove
# apt-get remove libapache2-mod-php5 php-db php-pear php5 php5-cli php5-common php5-gd php5-mcrypt php5-mysql php5-xsl
# apt-get autoremove
Add php5-mcrypt
# nano /etc/apt/preferences.d/php
put these lines :
Package: php5-mcrypt
Pin: release a=karmic
Pin-Priority: 991at the bottom.
Update repository and reinstall PHP
#apt-get update
#apt-get install php5 libapache2-mod-php5 php-db php5-cli php5-common php5-xsl php5-gd php-pear php5-mysql php5-curl php5-memcache php5-mcrypt
Check PHP version
# php -v
PHP 5.2.10-2ubuntu6 with Suhosin-Patch 0.9.7 (cli) (built: Oct 23 2009 16:30:10)
Copyright (c) 1997-2009 The PHP Group
Zend Engine v2.2.0, Copyright (c) 1998-2009 Zend Technologies
#
Great.
PHP successfully downgrade to 5.2.10 on Ubuntu 10.10 x86