Julien Claassen wrote: > I just wondered, if it would be possible to downgrade my Debian > distro from - say - Wheezy to Squeeze? I thought, that it must work, > but I can't for the life of me think, which exact command to use. No. That operation is not supported. It would be almost impossible to test all of the cases. And the need for doing so is much rarer. Upgrading is a task that everyone needs, at least for security upgrades. But downgrading is uncommon. An individual project package might downgrade just fine. But taking the entire system back would be very unlikely to be completely successful. The problem comes down to migration of configuration files and migration of system configuration. When upgrading the postinst script is coded to transition forward in time from older formats to newer formats. And if there is a particularly troublesome problem at some revision then specific cases can be coded around. The newer package knows about the problems that were created in the older package. Downgrading is the opposite case. Now the older package would need to know how to back out things that happen in the newer package. But at the time that the older package was written the newer package had not been created yet. Therefore in the general case it is impossible for the older package to be able to handle all potential issues. For packages without any configuration files or anything except executables in /usr/bin and documentation in /usr/share/doc the downgrade will be trivial and will always work as expected. But for other more complicated packages it might be required to purge, re-install, then reconfigure. Over the entire system from something with as many changes as going from Squeeze to Wheezy and then back this would be impossible. Take for example the scripts that convert to the new tmpfs /run configuration. All of that would need to be undone. That is too much to ask. Bob
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