要把ubuntu 系统里的php 从 5.3 或更高版本降到低版本 5.2 。搜了很多资料，千篇一律都有问题，估计都没试过，ubuntu 的karmic 源地址基本上都失效了。这里提供一个修改后的脚本。
#!/bin/bash
echo "Am I root? "
if [ "$(whoami &2>/dev/null)" != "root" ] && [ "$(id -un &2>/dev/null)" != "root" ] ; then
echo " NO!
Error: You must be root to run this script.
Enter
sudo su
"
exit 1
fi
echo " OK";
#install aptitude before, if you don`t have it:
apt-get install aptitude
# or if you prefer apt-get use:
# alias aptitude='apt-get'
# finish all apt-problems:
aptitude update
aptitude -f install
#apt-get -f install
# remove all your existing PHP packages. You can list them with dpkg -l| grep php
PHPLIST=$(for i in $(dpkg -l | grep php|awk '{ print $2 }' ); do echo $i; done)
echo these pachets will be removed: $PHPLIST
# you need not to purge, if you have upgraded from karmic:
aptitude remove $PHPLIST
# on a fresh install, you need purge:
# aptitude remove --purge $PHPLIST
#Create a file each in /etc/apt/preferences.d like this (call it for example /etc/apt/preferences.d/php5_2);
#
#Package: php5
#Pin: release a=karmic
#Pin-Priority: 991
#
#The big problem is that wildcards don't work, so you will need one such stanza for each PHP package you want to pull from karmic:
echo ''>/etc/apt/preferences.d/php5_2
for i in $PHPLIST ; do echo "Package: $i
Pin: release a=karmic
Pin-Priority: 991
">>/etc/apt/preferences.d/php5_2; done
# duplicate your existing sources.list replacing lucid with karmic and save it in sources.list.d:
#sed s/lucid/karmic/g /etc/apt/sources.list | sudo tee /etc/apt/sources.list.d/karmic.list
# better exactly only the needed sources, cause otherwise you can get a cachsize problem:
echo "# needed sources vor php5.2:
deb http://old-releases.ubuntu.com/ubuntu/ karmic main restricted
deb-src http://old-releases.ubuntu.com/ubuntu/ karmic main restricted
deb http://old-releases.ubuntu.com/ubuntu/ karmic-updates main restricted
deb-src http://old-releases.ubuntu.com/ubuntu/ karmic-updates main restricted
deb http://old-releases.ubuntu.com/ubuntu/ karmic universe
deb-src http://old-releases.ubuntu.com/ubuntu/ karmic universe
deb http://old-releases.ubuntu.com/ubuntu/ karmic-updates universe
deb-src http://old-releases.ubuntu.com/ubuntu/ karmic-updates universe
deb http://old-releases.ubuntu.com/ubuntu/ karmic multiverse
deb-src http://old-releases.ubuntu.com/ubuntu/ karmic multiverse
deb http://old-releases.ubuntu.com/ubuntu/ karmic-updates multiverse
deb-src http://old-releases.ubuntu.com/ubuntu/ karmic-updates multiverse
deb http://old-releases.ubuntu.com/ubuntu karmic-security main restricted
deb-src http://old-releases.ubuntu.com/ubuntu karmic-security main restricted
deb http://old-releases.ubuntu.com/ubuntu karmic-security universe
deb-src http://old-releases.ubuntu.com/ubuntu karmic-security universe
deb http://old-releases.ubuntu.com/ubuntu karmic-security multiverse
deb-src http://old-releases.ubuntu.com/ubuntu karmic-security multiverse
" > /etc/apt/sources.list.d/karmic.list
aptitude update
#apache2ctl restart
echo install new from karmic:
aptitude -t karmic install $PHPLIST
# at the end retry the modul libapache2-mod-php5 in case it didn't work the first time:
aptitude -t karmic install libapache2-mod-php5
#apache2ctl restart，本人使用nginx和fastcgi模式
apt-get install php5-cli php5-cgi php5-mysql
pkill -9 php-cgi
spawn-fcgi -a 127.0.0.1 -p 9000 -C 10 -u jimmy -f /usr/bin/php-cgi
service nginx restart
执行下面代码，告诉update-manager 不要再提醒更新php到高版本。
#!/bin/bash
for i in $(dpkg -l | grep php|awk '{ print $2 }' );
do echo "echo $i hold |sudo dpkg --set-selections"; echo $i hold |sudo dpkg --set-selections; done
如果希望更新到php高版本，则
#!/bin/bash
for i in $(dpkg -l | grep php|awk '{ print $2 }' );
do echo "echo $i install |sudo dpkg --set-selections"; echo $i install |sudo dpkg --set-selections; done