I found a set of commands that creates a list of installed packages on a machine, and then reinstall the same packages in another machine. It seems that the command works fine on Ubuntu 32bit desktop, but on Ubuntu amd64 (Desktop) the command
sudo apt-get dselect-upgrade tells me that I need to uninstall a lot of packages (including unity, unity-2d, unity-common) even if these packages appear in the list of installed packages in the first system.
Even if these commands are inputted in sequence on the same computer, they work fine in a 32 bit environment but seems to fail in a 64 bit environment. May be I missed something. Here's the commands in sequence:
sudo dpkg --get-selections > installed-software sudo dpkg --set-selections < installed-software sudo apt-get dselect-upgrade