apt (Debian & Ubuntu)

apt installs, updates and removes software on Debian-based systems.

Syntaxsudo apt [update|upgrade|install|remove] [package]

You rarely download software manually on Linux. Instead a package manager fetches programs and their dependencies from trusted online repositories. On Ubuntu and Debian that tool is apt.

The core commands

  • sudo apt update — refresh the list of available packages. Run this first.
  • sudo apt upgrade — install newer versions of what you have.
  • sudo apt install git — install a package.
  • sudo apt remove git — uninstall it.
  • apt search word — find packages by keyword.

update only refreshes the catalogue; upgrade actually installs the newer versions.

Example

Example · bash
# Refresh the catalogue, then upgrade everything
sudo apt update
sudo apt upgrade

# Install a package
sudo apt install curl

# Remove it and its unused dependencies
sudo apt remove curl
sudo apt autoremove

When to use it

  • A developer installs Node.js on an Ubuntu server with 'sudo apt install nodejs' without manually downloading a binary.
  • A sysadmin runs 'sudo apt upgrade' weekly in a cron job to keep all installed packages patched against security vulnerabilities.
  • A DevOps engineer uses 'apt list --installed' to audit which packages are present on a server before taking a snapshot.

More examples

Install and update packages

Shows the standard workflow: update index, install a package, then upgrade all packages non-interactively.

Example · bash
# Update the package index first
sudo apt update

# Install a package
sudo apt install nginx

# Upgrade all installed packages
sudo apt upgrade -y

Search and remove packages

Demonstrates searching, inspecting, and removing packages with the difference between remove and purge.

Example · bash
# Search for packages matching a name
apt search 'postgresql'

# Show details about a package
apt show nginx

# Remove package (keep config files)
sudo apt remove nginx

# Remove package AND config files
sudo apt purge nginx

Clean up unused packages

Shows maintenance commands for reclaiming disk space and auditing installed software.

Example · bash
# Remove automatically installed deps no longer needed
sudo apt autoremove

# Clear the downloaded package cache
sudo apt clean

# List installed packages
apt list --installed 2>/dev/null | grep nginx

Related

linux dnf yumlinux sudo

Discussion

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