Can you explain what systemd is and how it functions in a Linux system?

systemd is an initialization system and service manager in Linux that is responsible for starting and managing processes during system boot and operation.

Main functions of systemd:

• Parallel service startup to speed up boot time.
• Dependency management between services.
• Monitoring and restarting services in case of failures.
• Logging through integration with journald.
• Managing user sessions and devices.

systemd uses units — configuration files with extensions like .service, .socket, .target, etc., which describe how to start and control services.

Example of starting a service:

sudo systemctl start nginx.service

systemd significantly simplifies system management compared to traditional init scripts, providing more flexible and reliable service operation.