A Million Monkeys

I installed Ubuntu 10.04 on a few servers a while back, and instantly noticed a lot of problems with a few of our sites (that’s usually what happens when you do a major upgrade without reading any release notes!). I fairly quickly found out that the cause was that in Ubuntu 10.04, PHP is now running version 5.3 (it was 5.2 in previous releases).

Unfortunately, PHP 5.3 deprecates a few common features (see here for more info) which causes a lot of sites to just stop working, or act strangely.

I found that the best way to move forward was to downgrade PHP back to 5.2 while we could work out what the problem was with our sites (as is always the case in a fast moving development cycle, this was months ago and we haven’t got around to it yet). I found a really useful step by step guide to do this, and within 10 minutes the server was running 5.2 using the Ubuntu Karmic sources.

The guide can be found at http://mrkandy.wordpress.com/2010/04/16/install-php-5-2-x-in-ubuntu-10-04-lucid/ and I have to give all credit to the writer of that article. None of this was my own work, I just stumbled across the post above and it fixed all my problems (I’m hoping that it’ll help out some of my readers as well).

Anyway, here are the steps. It basically does the following: Remove all PHP packages, pin all PHP packages to karmic, add karmic to sources, and then reinstall the PHP packages which were previously installed.

php_installed=`dpkg -l | grep php| awk '{print $2}' |tr "\n" " "`

# remove all php packge
sudo aptitude purge $php_installed

# use karmic for php pakage
# pin-params:  a (archive), c (components), v (version), o (origin) and l (label).
echo -e "Package: php5\nPin: release a=karmic\nPin-Priority: 991\n"  | sudo tee /etc/apt/preferences.d/php > /dev/null
apt-cache search php5-|grep php5-|awk '{print "Package:", $1,"\nPin: release a=karmic\nPin-Priority: 991\n"}'|sudo tee -a /etc/apt/preferences.d/php > /dev/null
apt-cache search -n libapache2-mod-php5 |awk '{print "Package:", $1,"\nPin: release a=karmic\nPin-Priority: 991\n"}'| sudo tee -a /etc/apt/preferences.d/php > /dev/null
echo -e "Package: php-pear\nPin: release a=karmic\nPin-Priority: 991\n"  | sudo tee -a /etc/apt/preferences.d/php > /dev/null

# add karmic to source list
egrep '(main restricted|universe|multiverse)' /etc/apt/sources.list|grep -v "#"| sed s/lucid/karmic/g | sudo tee /etc/apt/sources.list.d/karmic.list > /dev/null

# update package database (use apt-get if aptitude crash)
sudo apt-get update

# install php
sudo apt-get install $php_installed
# or sudo aptitude install -t karmic php5-cli php5-cgi //for fcgi
# or  sudo apt-get install -t karmic  libapache2-mod-php5 //for apache module

sudo aptitude hold `dpkg -l | grep php5| awk '{print $2}' |tr "\n" " "`
#done

And that’s it. As I said previously, all credit should go to the author of this post.

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If you install and uninstall a lot of packages using apt, aptitude, or dpkg, you may find that you end up with a lot of redundant packages, or ones which have been uninstalled but the config files are left behind.

You can find packages which have been removed but still have config files by running (basically the status field will be ‘rc’):

dpkg -l | grep “^rc”

Or, suppose you installed mysql 5.1 from my previous post using the dotdeb repositories and wanted to see a list of what was installed:

dpkg -l | grep dotdeb

Now, removing those packages is easy, all you need to do is pass the list to dpkg –purge using awk in a similar way to grep above, so the 2 examples above would become:

dpkg --purge `dpkg -l | awk '/^rc/{print $2}'`
dpkg --purge `dpkg -l | awk '/dotdeb/{print $2}'`

(note that you may need to delete and retype the backticks depending on how cut and paste is handled)

Using the methods above, it should be easy to clean up your system.

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For debian/ubuntu users who want to use MySQL 5.1, there aren’t really many options available apart from compiling from source.

Whilst this is probably the best solution, a far simpler and easier (no need to worry about things like the client) method is using the repositories from dotdeb.org. Although these are made for debian installs, I tried it earlier on ubuntu 8.10 and it worked without any problems. As usual, back up your data first!

Assuming you’ve got mysql-server-5.0 installed (although if you don’t have the server installed at all it should still work), here are the steps to get 5.1.

First, you need to edit /etc/apt/sources.list and add the dotdeb repository. This is the line you need to add for Lenny, but just change it to Etch if you haven’t upgraded yet (see my earlier post if you want to know how to do that)

deb http://packages.dotdeb.org lenny all

Then, update…

apt-get update

And then install 5.1

apt-get install mysql-server-5.1

This should also install the dependancies: libmysqlclient16, mysql-client-5.1, and update mysql-common. If you already have 5.0 installed, this will also remove the server and client for it.

If you get a message saying that packages can’t be authenticated, it isn’t anything to worry about. Just select ‘y’ and continue. After the install is complete, you should have MySQL 5.1 installed with the most useful engines:

Server version: 5.1.32-0.dotdeb.0 (Debian)

You can also use the dotdeb repositories to upgrade to the latest versions of apache, and php.

It’s probably worth reading this guide on apt pinning, which is the best way to maintain a system using repositories with different versions of the same packages.

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