apt/dpkg Cheatsheet

apt

apt can be considered a front-end to dpkg.

apt is a simplified command that combines the most commonly used command options from apt-get and apt-cache.

apt Commands

$ sudo apt install <package>
$ sudo apt install <package>=<version>    # Install a specific version
$ sudo apt search <package>
$ sudo apt show <package>
$ sudo apt update
$ sudo apt list --upgradable
$ sudo apt list --installed
$ sudo apt upgrade
$ apt-cache stats: get stats of the packages
$ apt-cache pkgnames | grep docker

How to list available packages

# list available packages
$ apt-cache search KEYWORD

# e.g. search for Chrome
$ apt-cache search google-chrome
google-chrome-stable - The web browser from Google

$ apt install google-chrome-stable

apt update vs apt upgrade vs apt dist-upgrade

• apt update will only check the latest versions of the packages, without actually downloading package updates;
• apt upgrade will do the actual upgrading;
• apt dist-upgrade is for upgrading the OS itself.

dpkg (Debian Package Manager)

Install a local .deb package in Ubuntu:

$ dpkg -i filename.deb

List pakcages:

$ dpkg -l

Check all installed packages

$ dpkg --get-selections
$ dpkg --get-selections | grep mongo

dpkg is a backend-ish tool, usually we do not need to use it directly. Check other options in $ man dpkg.

check where the command is coming from

$ dpkg -S /bin/ls

$ dpkg -S $(which ls)

$ dpkg -S /usr/bin/ssh
openssh-client: /usr/bin/ssh

$ dpkg -S /bin/grep
grep: /bin/grep

Note that

• -S for search
• -s for status

Get details about the package:

$ dpkg -s coreutils
coreutils: /bin/ls

error: parsing file ... near line 0

Error:

dpkg: error: parsing file '/var/lib/dpkg/updates/0004' near line 0:

Verify:

$ head /var/lib/dpkg/updates/0004
#padding
#padding
#padding
#padding

Fix:

$ cd /var/lib/dpkg/updates && rm -rf 0004
$ sudo dpkg --configure -a

FAQ

Where do the packages come from?

They come from "repositories" listed in

• /etc/apt/sources.list
• /etc/apt/sources.list.d/

Personal Package Archives (PPAs) are software repositories designed for Ubuntu users and are easier to install than other third-party repositories. PPAs are often used to distribute pre-release software so that it can be tested.

Where to find apt/dpkg history?

The apt history is in /var/log/apt/history.log

To see all the packages that went through dpkg, you can look at /var/log/dpkg.log.