I ran aptitude from the terminal, and it said that I have 69,000 uninstalled packages. Can they safely be deleted without affecting system stability or functionality?
No doubt those packages wasn't installed in your system to be uninstalled and deleted!!!
This number in deed is number of packages available in your added repositories.
But you should know a concept when installing a package first it will download its
/var/cache/apt/archives and then install this package. So indeed when you install a package its
.deb binary is still available in the above directory. This directory could be cleaned using commands:
sudo apt-get clean
sudo apt-get autoclean
Also another important concept sometimes you install some package which needs some other dependencies. So to install this package you need to install that dependencies. Now suppose you remove this package, then its dependencies is not used anymore and you can delete them using command:
sudo apt-get autoremove
I am using Ubuntu 14.04. From time to time when I run
I see a message about unused packages and a suggestion to use
Which then cleans up the packages that are not needed. If there is really something that needs to be removed, the OS will probably let you know when you apply patches.