apt

Refreshes the repository package list. Always run this before installing or upgrading packages.

sudo apt update

Installs the specified package(s). Multiple packages can be specified separated by spaces.

sudo apt install {package} [{package} ...]

Installs a specific version of a package.

sudo apt install {package}={version}

Updates all installed packages to the latest version. Adds new dependency packages as needed, but does not remove existing packages.

sudo apt upgrade

Updates the entire system, removing existing packages if necessary. Use this for major changes such as kernel updates.

sudo apt full-upgrade

Removes the package (configuration files are kept). Use purge to remove the package along with its configuration files.

sudo apt remove {package}
sudo apt purge {package}

Removes dependency packages that are no longer needed.

sudo apt autoremove

Searches for packages by keyword. Use show to display detailed information such as version and dependencies.

apt search {keyword}
apt show {package}

Lists all installed packages, or lists packages that can be upgraded.

apt list --installed
apt list --upgradable

Adds an Ubuntu PPA (Personal Package Archive). Run apt update after adding to refresh the package list.

sudo add-apt-repository ppa:{username}/{repository}
sudo apt update

Operation	Command	Description
Update package list	apt update	Refreshes the repository package list. Always run this before installing or upgrading packages.
Install a package	apt install {package}	Installs the specified package. Dependencies are resolved automatically.
Upgrade all packages	apt upgrade	Updates all installed packages to the latest version. Does not remove existing packages.
Full upgrade	apt full-upgrade	Updates the entire system, allowing removal of existing packages if necessary. Used for kernel updates and similar changes.
Remove a package	apt remove {package}	Removes the package. Configuration files remain on the system.
Remove with config files	apt purge {package}	Removes the package along with its configuration files. Use this for a complete reset.
Remove unused dependencies	apt autoremove	Removes dependency packages that are no longer needed. Running this after remove or purge frees up disk space.
Search for a package	apt search {keyword}	Searches package names and descriptions by keyword.
Show package details	apt show {package}	Displays detailed information including version, dependencies, and description.
List installed packages	apt list --installed	Lists all packages currently installed on the system.
List upgradable packages	apt list --upgradable	Shows all packages that can be upgraded after running apt update.
Install a specific version	apt install {package}={version}	Installs a pinned version of a package. Useful when you need to keep a version that has been tested and verified.
Add a PPA repository	add-apt-repository ppa:{user}/{repo}	Adds an Ubuntu PPA. Allows you to use software versions not available in the official repositories.
Remove a PPA repository	add-apt-repository --remove ppa:{user}/{repo}	Removes an added PPA. Run apt update after removing to refresh the package list.

Update the system to the latest state

Refresh the package list, then update all installed packages. You can also check which packages are upgradable beforehand.

$ sudo apt update
$ sudo apt upgrade
$ apt list --upgradable
Listing... Done
bash/jammy-updates 5.1-6ubuntu1.1 amd64 [upgradable from: 5.1-6ubuntu1]
libc6/jammy-updates 2.35-0ubuntu3.8 amd64 [upgradable from: 2.35-0ubuntu3.7]
openssl/jammy-updates 3.0.2-0ubuntu1.18 amd64 [upgradable from: 3.0.2-0ubuntu1.17]

Install Nginx and verify it works

Update the package list, install Nginx, then verify the installed version.

$ sudo apt update
$ sudo apt install nginx
$ nginx -v
nginx version: nginx/1.24.0 (Ubuntu)

Add a PHP PPA and install the latest version

Adding the PPA by Ondřej Surý makes newer PHP versions available than those in the official Ubuntu repository. software-properties-common is required because it provides the add-apt-repository command.

$ sudo apt install software-properties-common
$ sudo add-apt-repository ppa:ondrej/php
$ sudo apt update
$ sudo apt install php8.3 php8.3-fpm php8.3-mbstring php8.3-xml php8.3-curl
$ php8.3 --version
PHP 8.3.6 (cli) (built: Apr 15 2024 18:34:22) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.3.6, Copyright (c) Zend Technologies
    with Zend OPcache v8.3.6, Copyright (c), by Zend Technologies

Cleanly remove an unnecessary package

Remove apache2 along with its configuration files, then clean up dependencies and cached package files. apt clean deletes .deb files under /var/cache/apt/archives/.

$ sudo apt purge apache2
$ sudo apt autoremove
$ sudo apt clean
$ apt list --installed | grep apache2
(No output means the removal was successful)

Install a specific version of a package

Check available versions first, then install the package at a pinned version.

$ apt-cache policy nginx
nginx:
  Installed: 1.24.0-1ubuntu1
  Candidate: 1.24.0-1ubuntu1
  Version table:
 *** 1.24.0-1ubuntu1 500
        500 http://jp.archive.ubuntu.com/ubuntu jammy-updates/main amd64 Packages
     1.18.0-6ubuntu14 500
        500 http://jp.archive.ubuntu.com/ubuntu jammy/main amd64 Packages
$ sudo apt install nginx=1.18.0-6ubuntu14
$ nginx -v
nginx version: nginx/1.18.0 (Ubuntu)

apt is a high-level package management tool for Debian- and Ubuntu-based Linux systems. It sits on top of the lower-level tool dpkg, and handles dependency resolution, downloading from repositories, and installation all in one step. Making a habit of running apt update to refresh the package list before apt install helps prevent dependency conflicts. After uninstalling, running apt autoremove and apt clean removes leftover files and keeps the disk tidy. When you need a newer version of software not available in the official repositories (such as the latest PHP), you can add a PPA — but always verify that the source is trustworthy before doing so. For package management on RHEL- and AlmaLinux-based systems, see the dnf / yum page.