apt (Advanced Package Tool) is the standard Debian/Ubuntu package manager. It manages .deb files and their dependencies.

Update package lists from repositories:

sudo apt update

Install a package:

sudo apt install package-name

Remove package but keep config:

sudo apt remove package-name

Remove package and config files:

sudo apt purge package-name

Upgrade installed packages:

sudo apt upgrade

Upgrade including dependency changes (riskier):

sudo apt full-upgrade

Find packages:

apt search keyword
apt search --names-only keyword

Show package details:

apt show package-name

List installed packages:

dpkg -l
dpkg -l | grep keyword

List files in a package:

dpkg -L package-name

Check if package is installed:

dpkg -l package-name

apt-get is the older CLI with identical functionality:

apt-get update
apt-get install package-name

Prefer apt for interactive use; apt-get for scripts (stable interface).

• Always run sudo apt update before installing to ensure fresh metadata
• Use sudo apt autoremove to clean up unused dependencies
• sudo apt-cache search is equivalent to apt search
• Check for broken packages: sudo apt check
• Hold a package from upgrades: sudo apt-mark hold package-name
• Unhold: sudo apt-mark unhold package-name

apt is wrapper around dpkg (lower-level) and apt-cache (search). For most purposes, apt is sufficient.