Can you explain what system signals are and how they are used in operating systems?

System signals are mechanisms for interaction between processes and the operating system, allowing asynchronous notifications about events. Signals are used to control processes, handle errors, and other system events.

For example, when a user presses Ctrl+C in the terminal, the operating system sends the process a SIGINT signal, which usually results in the process being interrupted.

Main features of signals:

• Asynchronous: a signal can arrive at any moment.
• Handling: a process can set a signal handler or use default behavior.
• Types of signals: SIGTERM (request to terminate), SIGKILL (forceful termination), SIGSTOP (pause), SIGCONT (resume), etc.

Using signals allows for efficient process management, proper shutdown, reloading configuration without stopping, and reacting to system events.