Update the package lists
apt-get update
Install a .deb file/package
dpkg -i PACKAGENAME
Install a specific version
apt-get install ansible=2.2.1.0-1ppa~trusty
Show a list of all installed packages
dpkg --get-selections
Display installed files of a package
dpkg -L PACKAGENAME
Find which package owns a file
dpkg -S FILENAME
Display package description/summary/details of installed package
dpkg -s PACKAGENAME
Show package(s) and version only
dpkg-query -W "*xv*"
Show package version and dependencies
dpkg-query -W -f='${binary:Package}\t${Version}\t${Depends}\n' curl
Show package dependents
apt-cache rdepends curl
Show package dependents that are currently installed
apt-cache rdepends --installed curl
Show transitive dependencies at a dot graph
debtree curl
List packages matching wildcard
dpkg-query -l "python*"
List contents
dpkg -c file.deb
Manually extract
dpkg-deb -xv file.deb /dest/path/
Display package details for packages, including those available in repos that aren't installed
apt-cache show PACKAGENAME
Search for package or package description
apt-cache search "Text-to-search"`
Show all package versions, and their url, across all repos
apt-cache showpkg PACKAGENAME
Blocked updates are updates that will change the status (possibly removing) another installed package, or install additional new packages.
They will not be installed if you do a sudo apt-get upgrade. Instead they will be listed as packages "kept back".
The following will install them and automatically resolve the status changes (eg: by removing other packages/adding new packages):
sudo apt-get dist-upgrade
apt-get will use your http_proxy and ftp_proxy environment variables, but make sure /etc/sudoers (edit with sudo visudo) has the following line
Defaults env_keep = "http_proxy ftp_proxy"