Will 'aptitude upgrade or dist-upgrade' downgrade manually installed deb package?
 

Let's say I download the latest source codes, create a deb package using checkinstall and install the package with 'dpkg -i', but the package version in the depositary is of a older version. Will doing a 'aptitude upgrade or dist-upgrade' actually downgrade the installed latest version to the older version found in the depositary?

Thanks.

No, it only upgrades to a newer version.

Ask apt! It has a nice "don't do it, just pretend": apt-get --help | grep simulation. Most (at least some) other programs call this "dry-run". Use that to see what it wants to do.

apt-cache policy <package name> will answer this as well.