I normally download all .deb packages and just copy the packages from /var/cache/apt/archives directory to the rest of the computers, saving me to have to download all the updates and programs again. But since Ubuntu 11.04, the directory keeps deleting the oldest file or some kind of delete method that literally resets the amount of packages there. So then I need to download them agina on the rest of the PCs. The files stay there for a couple of days but then "magic" not there anymore after some days. So what do I need to do to tell Ubuntu NOT to eliminate any files from /var/cache/apt/archives, not even the previous versions of the same package. I do not want for it to delete anything from there.
Just to add, I install packages using aptitude or synaptic.