Services & your first website

Everything so far leads here. You'll install a real web server, start it, open the firewall, and publish your own page. This is where the family differences stack up, so it's the perfect final exam for Unit 3.

Services and systemctl

A service (old-school name: daemon) is a program that runs quietly in the background, waiting for work. sshd waits for logins and a web server waits for browsers. Both families use systemd to manage services, so these commands are identical:

systemctl status NAME           # is it running? (no sudo needed)
sudo systemctl start NAME       # start it now
sudo systemctl stop NAME        # stop it now
sudo systemctl restart NAME     # stop + start (after changing settings)
sudo systemctl enable NAME      # start automatically at boot
sudo systemctl enable --now NAME  # enable AND start, in one go

start means “right now” and enable means “every time the computer boots.” They're separate on purpose, which is why enable --now is so handy. (Lesson 15 goes much deeper: unit files, old-style service and /etc/init.d, and writing your own service.)

The Apache web server, two ways

Apache is one of the most popular web servers in the world, and it's the same software on both families. But look how many little things differ:

Build it: step by step

# 1. install
sudo dnf install -y httpd
# 2. start it now + at every boot
sudo systemctl enable --now httpd
# 3. open the firewall for web traffic
sudo firewall-cmd --permanent --add-service=http
sudo firewall-cmd --reload
# 4. write your page
echo '<h1>My first site</h1>' | sudo tee /var/www/html/index.html
# 5. test it
curl localhost

# 1. install (it starts by itself)
sudo apt update
sudo apt install -y apache2
# 2. check it's running
systemctl status apache2
# 3. firewall: allow SSH FIRST, then web, then turn it on
sudo ufw allow OpenSSH
sudo ufw allow 'Apache'
sudo ufw enable
# 4. write your page
echo '<h1>My first site</h1>' | sudo tee /var/www/html/index.html
# 5. test it
curl localhost

curl fetches a web page and prints its HTML. It's how admins test a web server without opening a browser. On a real network, you can then open http://SERVER-IP in any browser and see your page.

Try it: launch your site 🚀

Do it on one family, then switch families and do it again. Watch for the differences.

Quick check