Ubuntu – How does dpkg install a package

To set all packages currently selected to deinstall back to install, you run the following two commands:

sudo dpkg --get-selections | awk '/deinstall/ {printf "%s\t%s\n",$1,"install"}' > packages
sudo dpkg --set-selections < packages

The first command finds all packages marked with deinstall and writes a list of packages like this

package-name         install

The second command corrects the packages.

If the full output of dpkg --get-selections from before the accident is given, you can simply restore all selections with the command

sudo dpkg --set-selections < packages

where packages is the name of the file holding the old output.

Your dpkg has wrong version somehow, Ubuntu 18.04 currently has version 1.19.0.5. You need to reinstall dpkg:

Try this:

sudo -i
mkdir /tmp/dpkg
cd /tmp/dpkg
wget http://launchpadlibrarian.net/366329727/dpkg_1.19.0.5ubuntu2_amd64.deb
ar x dpkg*.deb data.tar.xz
tar xvf data.tar.xz ./usr/bin/dpkg
cp ./usr/bin/dpkg /usr/bin/
apt-get update
apt-get install --reinstall dpkg

From can't install software--can I fix missing dpkg?