Startup and init systems (systemd) in Linux CLI - Mini Project: Build & Apply

Basic systemd Service Setup and Management

📖 Scenario: You are managing a Linux server and want to create a simple service that runs a custom script at startup using systemd. This will help you automate tasks when the system boots.

🎯 Goal: Create a basic systemd service file to run a script at startup, enable the service, and check its status.

📋 What You'll Learn

Create a script file with a simple echo command

Create a systemd service file with correct sections and directives

Enable the service to start at boot

Start the service manually

Check the service status

💡 Why This Matters

🌍 Real World

Automating tasks on Linux servers or desktops to run scripts or programs at system startup.

💼 Career

System administrators and DevOps engineers often create and manage systemd services to control software and scripts on Linux systems.

1

Create the startup script

Create a file called /usr/local/bin/startup_script.sh with the content #!/bin/bash on the first line and echo "Startup script running" on the second line. Make sure the script is executable by running chmod +x /usr/local/bin/startup_script.sh.

Linux CLI

# Create the script file with the exact content and make it executable
# Your code here

Hint

Use a text editor like nano or vim to create the file, then run chmod +x /usr/local/bin/startup_script.sh to make it executable.

2

Create the systemd service file

Create a file called /etc/systemd/system/startup_script.service with the following content: under the [Unit] section, add Description=Startup Script Service; under the [Service] section, add ExecStart=/usr/local/bin/startup_script.sh; under the [Install] section, add WantedBy=multi-user.target.

Linux CLI

# Create the systemd service file with the exact sections and directives
# Your code here

Hint

Use a text editor to create the service file with the exact sections and lines as described.

3

Enable and start the service

Run the commands systemctl enable startup_script.service to enable the service at boot and systemctl start startup_script.service to start the service immediately.

Linux CLI

# Enable the service to start at boot
# Start the service now
# Your code here

Hint

Use systemctl enable to set the service to run at boot and systemctl start to run it now.

4

Check the service status

Run the command systemctl status startup_script.service and observe the output. The output should include the line Active: active (running) indicating the service is running.

Linux CLI

# Run the command to check the service status
# Your code here

Hint

Use systemctl status startup_script.service to see if the service is running.

Practice

1. What is the main purpose of systemd in a Linux system?

easy

A. To manage how the system starts and stops programs automatically

B. To edit text files in the system

C. To compile software from source code

D. To monitor network traffic

Solution

1. Step 1: Understand systemd's role

   systemd is a system and service manager that controls how programs start and stop on Linux.

2. Step 2: Compare options

   Only To manage how the system starts and stops programs automatically describes managing startup and shutdown of programs, which matches systemd's purpose.

3. Final Answer:

   To manage how the system starts and stops programs automatically -> Option A

4. Quick Check:

   systemd manages startup and shutdown = B [OK]

Hint: Remember: systemd controls startup and shutdown of services [OK]

Common Mistakes:

• Confusing systemd with text editors
• Thinking systemd compiles code
• Mixing systemd with network tools

2. Which of the following is the correct command to enable a service named nginx to start automatically at boot?

easy

A. systemctl enable nginx

B. systemctl start nginx

C. systemctl status nginx

D. systemctl stop nginx

Solution

1. Step 1: Understand systemctl commands

   To enable a service to start at boot, the command is systemctl enable [service].

2. Step 2: Match command to action

   systemctl enable nginx uses enable with nginx, which is correct for auto-start.

3. Final Answer:

   systemctl enable nginx -> Option A

4. Quick Check:

   Enable means auto-start = A [OK]

Hint: Enable means auto-start at boot, start means immediate run [OK]

Common Mistakes:

• Using start instead of enable for auto-start
• Confusing status with enable
• Using stop instead of enable

3. What will be the output of the command systemctl is-active sshd if the SSH service is running?

medium

A. inactive

B. failed

C. active

D. unknown

Solution

1. Step 1: Understand systemctl is-active

   This command checks if a service is running and returns its state.

2. Step 2: Identify expected output when running

   If the SSH service is running, the output is active.

3. Final Answer:

   active -> Option C

4. Quick Check:

   Running service status = active [OK]

Hint: Active means running, inactive means stopped [OK]

Common Mistakes:

• Confusing active with inactive
• Expecting failed when service is running
• Thinking unknown means running

4. You run systemctl enable apache2 but the service does not start on boot. What is the most likely reason?

medium

A. The service is already running

B. You used start instead of enable

C. The systemctl command is not installed

D. The service file for apache2 is missing or incorrect

Solution

1. Step 1: Understand what enable does

   Enable creates links so the service starts at boot but does not start it immediately.

2. Step 2: Identify why enable might fail

   If the service file is missing or broken, enabling won't work properly, so it won't start on boot.

3. Final Answer:

   The service file for apache2 is missing or incorrect -> Option D

4. Quick Check:

   Missing service file blocks enable = D [OK]

Hint: Enable needs a valid service file to work [OK]

Common Mistakes:

• Confusing enable with start
• Assuming systemctl is missing
• Thinking running service means enable failed

5. You want to create a custom service that runs a script at startup. Which two steps must you perform to make sure it starts automatically with systemd?

hard

A. Add your script to /etc/rc.local and make it executable

B. Create a service file in /etc/systemd/system, then run 'systemctl enable yourservice' to auto-start it

C. Place your script in /usr/bin and reboot the system

D. Run 'systemctl start yourservice' and then 'systemctl status yourservice' only

Solution

1. Step 1: Create a systemd service file

   Write a service file describing your script and place it in /etc/systemd/system/ to define how systemd runs it.

2. Step 2: Enable the service

   Run systemctl enable yourservice to make it start automatically at boot.

3. Final Answer:

   Create a service file in /etc/systemd/system, then run 'systemctl enable yourservice' to auto-start it -> Option B

4. Quick Check:

   Create service file + enable = auto-start [OK]

Hint: Create service file and enable it to auto-start [OK]

Common Mistakes:

• Only starting service without enabling
• Using old /etc/rc.local method
• Placing script without service file