What is a system call in an operating system?
a) A function call by the user to the operating system
b) A mechanism to request services from the kernel
c) A method for executing user programs
d) A process to manage CPU scheduling
Answer:
b) A mechanism to request services from the kernel
Explanation:
A system call is a way for user programs to request services from the operating system’s kernel. It provides an interface between a process and the operating system to perform low-level tasks such as file handling, memory management, and process control.
System calls are typically invoked when a user program requires hardware access or system resources, which cannot be done directly by user programs due to security and privilege restrictions.
Examples of system calls include opening or closing a file, creating a new process, and allocating memory. System calls are essential for the safe and efficient execution of user programs in an OS.