oam/knowledge base/apt.md

The APT package manager

Table of contents

1. TL;DR
2. Automate security upgrades
3. Configuration
4. Version pinning
5. Troubleshooting
   1. Fix a "Problem with MergeList" or "status file could not be parsed" error
6. Further readings
7. Sources

TL;DR

# Check for broken dependencies.
sudo apt-get check

# Update the packages lists.
sudo apt update

# Upgrade the system.
sudo apt upgrade
sudo apt dist-upgrade

# Look for packages.
apt search 'ansible'
apt search --names-only 'python'

# Show details of packages.
apt show 'vlc'

# List a package's dependencies.
apt depends 'ufw'

# Install packages.
sudo apt install 'nano' 'python3-zstd/stable'

# Remove packages.
sudo apt remove 'dhclient' 'sudo'
sudo apt remove --purge 'bluez'
sudo apt purge 'crda'

# Remove orphaned packages.
sudo apt autoremove --purge

# List packages.
sudo apt list
sudo apt list --upgradable
sudo apt list --installed

# List explicitly installed packages only.
sudo apt-mark showmanual

# Mark packages as explicitly installed.
sudo apt-mark manual 'vim' 'unattended-upgrades'

# List non-explicitly installed packages only.
sudo apt-mark showauto

# Mark packages as non-explicitly installed.
sudo apt-mark auto 'zsh' 'bash-completion'
sudo apt-mark auto $(sudo apt-mark showmanual)

# Reconfigure packages.
sudo dpkg-reconfigure 'mariadb-server'
sudo dpkg-reconfigure -p 'low' 'unattended-upgrades'

Automate security upgrades

Leverage unattended-upgrades for this.

# Configure the packages to keep up to date.
sudo dpkg-reconfigure -p 'low' 'unattended-upgrades'

# Check what packages would be installed.
sudo unattended-upgrade -d --dry-run

# Run manually.
sudo unattended-upgrade

Configuration

See Apt configuration for more information.

# /etc/apt/apt.conf.d/90default-release
APT::Default-Release "stable";

# /etc/apt/apt.conf.d/99parallel-fetch
APT::Acquire::Queue-Mode "access";
APT::Acquire::Retries 3;

Version pinning

See apt_preferences's man page for more information.

# /etc/apt/preferences.d/99perl
Package: perl
Pin: version 5.20*
Pin-Priority: 1001

# /etc/apt/preferences.d/90debian-release
Package: *
Pin: release a=testing
Pin-Priority: 990
Package: *
Pin: release a=stable
Pin-Priority: 500
Package: *
Pin: release a=unstable
Pin-Priority: -1

# /etc/apt/preferences.d/boinc
Package: boinc boinc-client boinc-manager libboinc7
Pin: release a=unstable
Pin-Priority: 995

Troubleshooting

Fix a "Problem with MergeList" or "status file could not be parsed" error

E: Encountered a section with no Package: header E: Problem with MergeList /var/lib/apt/lists/deb.debian.org_debian_dists_bullseye_main_i18n_Translation-en E: The package lists or status file could not be parsed or opened.

sudo rm -vrf '/var/lib/apt/lists/'*
sudo apt update

Further readings

• Apt configuration
• Configuring Apt sources
• Unattended Upgrades
• apt_preferences's man page
• dpkg
• apt-file to look for files in packages
• netselect-apt to select the fastest APT mirror

Sources

All the references in the [further readings] section, plus the following:

• cheat.sh
• Fix a "Problem with MergeList" or "status file could not be parsed" error