Stop 03 · Linux & Scripting BasicsTopics · 3/9

Package Managers

In short

A fresh cloud VM has almost nothing installed. Nginx, Docker, Python, Git: all of it comes through the package manager. One command, the right version, and every dependency sorted for you.

Tools for installing, updating and removing software on Linux — apt on Debian/Ubuntu-based systems, yum/dnf on RHEL/CentOS-based systems — a core skill for configuring any cloud VM.

The blob character waits at a grocery counter while the shopkeeper picks packets off shelves.

Think of it like this

The kirana store list

You don't visit five factories for atta, oil and soap. You tell the kirana uncle 'one Maggi', and he picks the right packet from his shelves and maybe reminds you about the tastemaker. A package manager is that shopkeeper for software.

Watch it happen

What apt install really does

You

apt

Ubuntu repo

sudo apt update

1/6First, refresh the local catalogue of what's available. This doesn't install anything yet.

The big ideas

What you need to know

One tool per family

Ubuntu and Debian use apt. Amazon Linux, RHEL and Fedora use dnf (older ones use yum). Alpine uses apk.

Update the list first

apt update refreshes what's available. apt upgrade actually installs newer versions of what you have.

Dependencies handled

The manager installs everything a package needs, at compatible versions, so you don't hunt for libraries yourself.

Signed and trusted

Repos sign their packages. Adding random third-party repos means trusting whoever runs them.

See it in code

Walk through the code

bash

1# Ubuntu / Debian2sudo apt update3sudo apt install -y nginx git4apt list --installed | grep nginx5sudo apt remove nginx6 7# Amazon Linux 2023 / RHEL / Fedora8sudo dnf install -y nginx git9dnf list installed nginx

1/3Refresh the catalogue, then install two packages in one go.

-y answers 'yes' automatically, which you need in scripts and server setup that run without a human.

Save yourself the pain

Common mistakes

Oops

Running apt install on a fresh VM and getting 'Unable to locate package'.

Do this instead

Run sudo apt update first. A new machine's package list is often empty or stale.

Oops

Using apt commands on Amazon Linux because a tutorial said so.

Do this instead

Check the OS with cat /etc/os-release, then use the matching manager: dnf there, apt on Ubuntu.

Your mission

Set up a web server from scratch

~25 min

Quick check

What does sudo apt update do?

Go deeper

1Practice installing, updating, and removing a package using your distribution's package manager.
2Learn to search for available packages before installing something blindly.
3Practice this on both a Debian-based and RHEL-based VM if possible, to feel the syntax difference.