Maybe you have installed packages from a PPA or an external source (e.g. downloaded a .deb for a package that is available through the Ubuntu repos.).
Then you decide to drop these upgraded versions in favour to the official repositories.
First step is to remove the entries of the sources.list.
Is there a way to downgrade all to the highest available version? I know you can install specific versions with
apt-get install [package]=[version]But can you downgrade all?
A bit late to the party but I found this question when looking for an answer and now I have my own answer to share.
I believe you can do this via the mysterious world of apt_preferences.
Try making a file called /tmp/a_p (or whatever) like so...
Package: *
Pin: release a=*-backports
Pin-Priority: 100
Package: *
Pin: release n=*
Pin-Priority: 1001
Then run:
sudo apt-get -o Dir::Etc::Preferences=/tmp/a_p dist-upgrade
The second section of the file basically does what the OP requested, in that it bumps the priority of all packages in any live repository to make them install even if it means a downgrade.
The first section prevents the second section from triggering the installation of all backports. You may or may not care about or want this. I'd suggest tinkering to see what works. You can use apt-cache -o Dir::Etc::Preferences=/tmp/a_p policy somepkg to see what effect the a_p file is having on specific packages.
TIM
Ok, what if found is the script ppa-purge
If you added a PPA and upgraded software, you can remove the repo and in this step downgrade all packages that were upgraded with
ppa-purge [repo name]
Is this usefull for another person?
But it is still open if you can install the highest version available even if the installed version is higher...
sudo apt-get -y remove package1 package2 package3 && sudo apt-get install package1 package2 package3- I don't believe there is a single command such assudo apt-get repocleanfor example to do it.