System Calls and OS Concepts Quiz

A user-mode application requests file access using a system call. What is the first action taken by the OS in response?

• Switches to kernel mode

• Loads file metadata

• Displays an error code

• Launches the disk scheduler

Why are system calls necessary for resource access in a multi-user OS?

• To speed up I/O access

• To prevent GUI interruptions

• To maintain security and access control

• To bypass context switching

In Linux, a call to fork() results in two processes. How do the parent and child differ immediately after the system call?

• Different memory and PID

• Same memory and PID

• Parent has no access to child data

• Child runs in kernel mode

Which of the following is an example of a system call for process control?

• read()

• exec()

• mkdir()

• open()

A developer uses wait() after fork(). What happens if the wait() call is removed?

• Child terminates properly

• Parent never terminates

• Zombie process is created

• Kernel crashes

Why are system calls abstracted behind APIs like the C standard library?

• To increase syscall latency

• To simplify portability and code maintenance

• To directly map user memory

• To allow bypass of kernel mode

Which of the following best explains why system calls cannot be executed in user mode?

• They require low memory access

• They must interact with I/O directly

• They require elevated privileges and hardware access

• They are written in machine language only

A program repeatedly uses write() system calls in a loop without buffering. What is a likely consequence?

• Improved throughput

• Increased syscall overhead and CPU time

• Faster disk performance

• Reduced memory usage

A file system call like open() returns -1. What is the most likely reason?

• File is too large

• File not found or insufficient permissions

• File is already open

• System is out of RAM

Which of the following is not a valid category of system calls?

• Process control

• File manipulation

• Graphical rendering

• Communication