Install software on Ubuntu with APT: a beginner’s guide

Applies to: Ubuntu systems using APT · Time: About 10 minutes · Difficulty: Beginner

Ubuntu can install software from configured package repositories. APT looks up the package and handles its dependencies. This guide uses the small tree utility as a practice example. These commands are not intended for Fedora or Arch Linux.

Before you start

You need an internet connection and an account allowed to use sudo. On a work or school computer, follow your administrator’s software policy. Run each command separately and read the result before continuing.

1. Refresh the package list

Open Terminal and run:

sudo apt update

This refreshes information about available packages; it does not upgrade all installed software. If it reports download or repository errors, resolve those before installing.

2. Install one package

sudo apt install tree

Review the proposed package changes and download size. Confirm only if they match your intention. APT may install dependencies needed by the requested package.

3. Check the result

tree --version

A version message confirms that the command is available. This is a useful habit: an installation is not finished until you have checked the result you actually needed. For a graphical application, the equivalent check is opening it and trying its main function.

4. Remove the practice package if you wish

sudo apt remove tree

Review the removal list before confirming. Removing a package normally leaves its configuration files; purge also removes package configuration.

If you see an error

Copy the exact error into your notes, along with the command you ran. Check spelling before trying a different package name. Avoid pasting a chain of unrelated repair commands from several websites: a missing package and a network failure need different investigations.

If the error says there is no space left on the device, first check which filesystem is full and investigate folder sizes. That guide uses read-only reports; avoid deleting unfamiliar system or application folders just to retry an installation.

If you are unsure what a proposed change will remove, stop before confirming. The goal is to understand one small installation, not to change your whole system.

Sources

APT behavior is documented in Ubuntu’s package-management guide. Consult the package’s own documentation for application-specific behavior.

Optional gear

Affiliate disclosure: As an Amazon Associate I earn from qualifying purchases, at no extra cost to you. Commissions do not influence our recommendations.

Logitech K120 wired USB keyboard on Amazon (paid link). An optional full-size USB keyboard for terminal input. Check your device’s port and operating-system support; your existing keyboard is sufficient.

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You do not need to buy anything to follow this article. Check the exact model, seller and compatibility before buying.