On Linux servers, various services (such as web servers, databases, email services, etc.) need to be manually started to provide functionality and stopped to release resources. As a Linux newbie, mastering commands for starting, stopping, and checking the status of services is fundamental to server management. This article will explain these core commands in the simplest way to help you get started quickly.

一、What are Linux Services?¶

In simple terms, a service is a program that runs continuously in the background, such as:
- Nginx/Apache: Provides website access services
- MySQL/MariaDB: Provides database storage services
- SSH: Provides remote login services
- FTP: Provides file transfer services

These services need to be “started” to work properly and “stopped” to shut down or update.

二、Common Service Management Tool: systemctl (Must-Learn for Newbies)¶

Most modern Linux distributions (e.g., CentOS 7+/RHEL 7+/Ubuntu 16+) use systemd as the service management system, controlled by the systemctl command.
Core Format:

sudo systemctl [command] [service-name]

(sudo requires administrator privileges; regular users must add sudo to execute management commands.)

三、Detailed Explanation of systemctl Core Commands¶

四、Example: Managing Common Services¶

1. Start/Stop Web Server¶

• CentOS/RHEL: Web service name is httpd (Apache)

  sudo systemctl start httpd    # Start Apache
  sudo systemctl stop httpd     # Stop Apache

• Ubuntu/Debian: Web service name is apache2

  sudo systemctl start apache2  # Start Apache
  sudo systemctl stop apache2   # Stop Apache

2. Start/Stop Database Service¶

• CentOS/RHEL: Database service name is mariadb (MySQL alternative)

  sudo systemctl start mariadb  # Start MariaDB
  sudo systemctl stop mariadb   # Stop MariaDB

• Ubuntu/Debian: Database service name is mysql

  sudo systemctl start mysql    # Start MySQL
  sudo systemctl stop mysql     # Stop MySQL

3. Check Service Status¶

Use the status command to confirm if a service is running:

sudo systemctl status sshd  # Check SSH service status (universal for all systems)

• active (running) in the output indicates the service is running normally.
• inactive (dead) indicates the service is stopped.

4. Set Auto-Start on Boot¶

Make services start automatically on boot to avoid manual intervention:

sudo systemctl enable nginx  # Enable auto-start for Nginx
sudo systemctl disable nginx # Disable auto-start for Nginx

五、Common Issues and Solutions¶

1. Insufficient Permissions:
   Regular users will get “Permission denied” when running systemctl commands. Use sudo:

   sudo systemctl start nginx

2. Service Start Failure:
   Use status or logs to troubleshoot:

   sudo systemctl status [service-name]  # Check error messages
   sudo journalctl -u [service-name]    # View detailed logs (e.g., Nginx config errors)

3. Forgot Service Name:
   List all services with list-unit-files:

   systemctl list-unit-files | grep [service-keyword]  # e.g., grep nginx

六、Summary¶

• Core Commands: start/stop/restart/status/enable/disable
• Permissions: Require sudo or root privileges
• Service Name Differences: Service names may vary across distributions (e.g., CentOS httpd vs Ubuntu apache2)
• Troubleshooting Tips: Use status to check status and journalctl to view logs

Practice these commands repeatedly to master service management on your server!