👈

Linux has three types of users:

🔹 1. System users

Created automatically by Linux during OS installation.

Examples from your list:

root
bin
daemon
adm
mail
sshd
systemd-network
chrony
apache

✅ These users:

• Are used by the OS and services
• Cannot log in
• Usually have /sbin/nologin as their shell

Example:

sshd:x:74:74:Privilege-separated SSH:/usr/share/empty.sshd:/sbin/nologin

➡ SSH service runs as sshd user ➡ No human login allowed

🔹 2. Service / Application users

Created when software is installed.

Examples:

apache
dbus
rpc
tcpdump
ec2-instance-connect

Why they exist:

• For security
• Each service runs with limited permissions

Example:

apache:x:48:48:Apache:/usr/share/httpd:/sbin/nologin

➡ Apache web server runs as apache user

🔹 3. Normal (human) users 👤

These are real login users.

From your system:

ec2-user
devuser

✔ These users:

• Have /bin/bash
• Have home directories
• Can log in

Example:

devuser:x:1002:1002::/home/devuser:/bin/bash

2️⃣ You created only these users 👇

You said:

i create only two user devuser, rijuldev

That is correct ✅

These are the users you created:

rijuldev
devuser

Additionally:

ec2-user

➡ Created automatically by AWS EC2

🔍 who means:

"Show users currently logged in"

Right now:

• Only you are connected
• Probably via one SSH session
• No other users are logged in

So who output is empty or minimal 👉 This is normal

Try this:

whoami

You’ll see:

ec2-user

4️⃣ How to list only real login users?

🔹 Show users with /bin/bash

grep "/bin/bash" /etc/passwd

Output will be something like:

root
ec2-user
rijuldev
devuser

✔ These are actual login users

5️⃣ Summary (easy to remember 🧠)