Package managers

Ubuntu uses APT to install and update software from configured repositories. apt is intended for interactive administration; apt-get is commonly used where a more stable scripting interface is wanted.

sudo apt updatesudo apt upgradesudo apt full-upgradesudo apt install nginxsudo apt remove nginxsudo apt purge nginxsudo apt autoremoveapt search nginxapt show nginxapt list --installed

apt update downloads current package indexes but does not upgrade installed software. apt upgrade installs available upgrades without removing installed packages to satisfy dependencies. full-upgrade may remove packages when necessary to complete an upgrade.

remove uninstalls a package while normally leaving its configuration files. purge removes the package and package-managed configuration. autoremove removes dependencies that APT believes are no longer required.

For package files already downloaded:

sudo apt install ./package.debdpkg -ldpkg -L package-namedpkg -S /path/to/fileapt-cache policy package-name

Installing a local .deb with apt is usually preferable to dpkg -i because APT can resolve dependencies. dpkg -L lists files installed by a package and dpkg -S identifies which installed package owns a path. apt-cache policy shows installed and candidate versions and their repository sources.

Other Linux distributions use different package managers, including dnf on Fedora and RHEL-family systems, pacman on Arch Linux and zypper on openSUSE.