Managing Software Packages

Open Source software packages are maintained in repositories. Each release has a version number, and package dependencies are recorded so that matching versions of packages can be installed together. Occasionally software updates are not aligned perfectly, and an update to one program and its dependencies will break other installed programs.

This article explains how to manage installed and upgraded packages in an Ubuntu system using utility programs synaptic, dpkg, and apt-{anything}.

Hint

Display all the apt- programs at the console by typing apt-<Tab><Tab>.

General package rules

• Only one package management program may be run at a time. Do not,say, start synaptics in a window and try to run an apt- utility in a console terminal at the same time.
• Package programs require root privileges. Use sudo to execute all commands.
• Wild-card expressions are permitted in version numbers. When using versions, make sure the version expression uniquely selects the desired version from available cached packages.

Package management utilities

synaptics

Use the synaptics menu option File ‣ History to review package changes.

apt-get

sudo apt-get update && sudo apt-get upgrade
sudo apt-get install {package}={version}
sudo apt-get -f install

apt-cache

sudo apt-cache policy {package}

apt-mark

sudo apt-mark hold {package} --version {version}

apt-show-versions

apt-show-versions {package}

dpkg

sudo dpkg --configure -a

Special commands

Show all packages installed or upgraded in the past 3 days:

find /var/lib/dpkg/info/ -name \*.list -mtime -3 | sed `s#.list$##; s#.*/##`

Place a package on hold using a pin file:

sed -i 'Package: {program}\nPin: {version}\nPin-Priority: 1000' /etc/apt/preferences/{program/