download python-software-properties_0.75.4_all.deb from ubuntu repos and you can use launchpad to add rpos with the add-apt-repository command to add a ppa in automated fashion.
Sometimes you will need to edit the source file in etc/apt/sources.list.d directory
i use ubuntu-tweak to access these files and edit them easily
i did this to add things like bisigi themes (and others)
edit it to look like this:
# Bisigi
deb http://ppa.launchpad.net/bisigi/ppa/ubuntu lucid main
If you do do this with other repositories you could damage your system so be careful. Even after you edit some repos, not all packages will install/upgrade.
i also tend to copy everything over to the sources.list file in /etc/apt and delete the origional from /etc/apt/sources.list.d directory.. keeps thing neat and ubuntu-tweak does all this very easy from its source editory.
here's a snapshot of my sources.list file which you could just copy.
deb http://packages.linuxmint.com/ debian main upstream import backport romeo
deb http://ftp.debian.org/debian testing main contrib non-free
deb http://security.debian.org/ testing/updates main contrib non-free
deb http://www.debian-multimedia.org testing main non-free
# Chrome
deb http://dl.google.com/linux/chrome/deb/ stable main
deb http://dl.google.com/linux/deb/ stable non-free main
# Thumbnailer
deb http://ppa.launchpad.net/deb-thumbnaile ... ppa/ubuntu lucid main
# Opera
deb http://deb.opera.com/opera/ lenny non-free
# PlayonLinux
deb http://deb.playonlinux.com/ lucid main
# Skype
# deb http://download.skype.com/linux/repos/debian/ stable non-free
# get keys
# deb http://ppa.launchpad.net/nilarimogard/webupd8/ubuntu maverick main
# Remastersys Squeeze
deb http://www.geekconnection.org/remastersys/repository debian/
# Swiftfox
deb http://getswiftfox.com/builds/debian unstable non-free
# Bisigi
deb http://ppa.launchpad.net/bisigi/ppa/ubuntu lucid main
# Super OS
# deb http://hacktolive.org/repo/lucid lucid main restricted multiverse universe partner
# Boxee
deb http://apt.boxee.tv/ lucid main
# Get Deb Apps
# deb http://archive.getdeb.net/ubuntu lucid-getdeb apps
you'll notice i have some things commented out with a #, like get deb repo.. i installed boookwrite, xvst, homebank the commented out the line afterwards so it doesn't try to upgrade packages that would break my system.
same with super os.. a few files i wanted, installed and commented out..
under # Get keys is a repo that has a file called launchpad-getkeys that you could use if you copied my source list into yours.
uncomment the repo line by deleting the # in front of it.
sudo apt-get update
sudo apt-get install launchpad-getkeys
sudo launchpad-getkeys
this will add all the missing keys from any uncommented line (#)
i recommend comment that repo back by adding the # to the front of the repo source so you don't upgrade files that would break your system
*Use with caution*
Also, python-software-properties_0.75.4_all.deb will break synaptic in that you will not be able to access the repositories through synaptic through it's menu.
when you made all the changes you wanted and want to restore the repository access in synaptic, simple uninstall software-properties-gtk and python-software-properties-gtk and then reinstall them. the reason for this is the python is 0.75 and software is .6 and once they are both uninstalled and reinstalled, they will both be .6 versions and synaptic repo acces from the menu in it is restored. However, add-apt-repository command will now not work again. It's just how it is....
*USE CAUTION* and good luck...






