APT Command Tutorial: Install, Remove, Update Packages (Ubuntu & Debian)

The apt command is the main tool used to manage packages in Ubuntu and Debian-based Linux systems. In this tutorial, we’ll go over the basic commands you can use to search, install, remove, and update packages.

Listing Installed Packages

To list all available packages (both installed and not installed), run:

apt list

To only see installed packages:

apt list --installed

To check if a specific package is installed, you can filter the list using the grep command. For example, this command finds packages with 'ssh' in their name:

apt list --installed | grep ssh

Another way to list installed packages is by using the dpkg -l command:

dpkg -l

Searching for Packages to Install

You can use apt search to look for packages by keyword. For example, apt search apache will list all packages related to "apache."

apt search apache

NOTE: Before searching, it's good practice to update your local package index using the apt update command.

Sometimes, apt search can provide a very long output, and its multi-line format can make filtering with grep challenging. For more precise searches, especially when knowing specific terms, apt-cache search is often preferred as it presents results in a more grep-friendly single-line format.

Examples

To find Apache-related packages, you can run:

apt-cache search apache

Filter the output of the above command to find the lines that have 'server' in the package name or description:

apt-cache search apache | grep -i server

Installing Packages

Once you know the name of the package you want to install, use the apt install command to install it:

sudo apt install package-name

By default it will ask for a confirmation before installing a package. To skip the confirmation add -y option:

sudo apt install package-name -y

Example: Installing the Apache HTTP Server

First, it's always a good idea to update your local package index to ensure you have the latest information about available packages:

sudo apt update

Then install the apache2 package, which provides the Apache web server on Ubuntu:

sudo apt install apache2

Uninstalling Packages

To uninstall a package you can use either apt remove or apt purge commands.

• apt remove uninstalls the package but keeps its configuration files.
• apt purge removes the package along with its configuration files.

If you want to completely remove a package, use apt purge:

sudo apt purge package-name

After uninstalling a package, also run the apt autoremove command to remove any dependency packages that are no longer needed:

sudo apt autoremove

Example: Uninstalling the Apache web server:

sudo apt purge apache2
sudo apt autoremove

Updating Packages

To see which packages can be upgraded:

apt list --upgradable

To update all packages on your system, first refresh your package list, then run the apt upgrade command:

sudo apt update
sudo apt upgrade

The apt upgrade command updates all installed packages to their latest versions. If you only want to upgrade a single package, you can do so using the apt install command with the --only-upgrade option:

sudo apt install --only-upgrade package-name

Hold a package from being upgraded

To prevent a package from being upgraded, use the apt-mark hold command:

sudo apt-mark hold package-name

To allow the package to be upgraded again, use the apt-mark unhold command:

sudo apt-mark unhold package-name

Conclusion

That’s a quick overview of using the apt command to manage packages on Debian and Ubuntu systems. As a final note, you can find the configuration files for apt repositories in the /etc/apt/sources.list.d/ directory.