Linux

Question 1

Explain the concept of a “process” in Linux

Answer 1

• a process executes an instance of a program
• It has its own memory space, program counter, registers, and system resources.

Question 2

Describe the role of the Virtual File System (VFS) in Linux

Answer 2

• The Virtual File System (VFS) is a layer of abstraction that provides a consistent interface for interacting with different file systems.

Question 3

Discuss the Linux I/O model and the role of the I/O scheduler

Answer 3

• The Linux I/O model revolves around asynchronous I/O operations.
• The I/O scheduler manages the ordering of I/O requests

Question 4

Explain the Linux memory management system, including virtual memory, paging, and swapping

Answer 4

• Linux memory management involves virtual memory, where each process has its own virtual address space.

Question 5

What is the significance of system calls in Linux?

Answer 5

• Provide a controlled entry point for user programs to access low-level kernel functionalities, ensuring security and stability.

Question 6

Could you provide examples of common system calls and their role in interacting with the kernel?

Answer 6

• fork(): Creates a new process.
• open(): Opens a file and returns a file descriptor.
• read(): Reads data from a file descriptor.
• write(): Writes data to a file descriptor.
• execve(): Executes a new program.

Question 7

How does the kernel manage processes?

Answer 7

• The kernel manages processes through the Process Control Block (PCB)
• employs the scheduler to switch between processes, allowing multitasking and efficient resource utilization.

Question 8

How does Virtual File System provide an abstraction layer for various file systems?

Answer 8

• VFS abstracts away the underlying details of various file systems like ext4, NFS, and more, allowing applications to use common system calls for file operations.
• VFS uses a set of function pointers to redirect these calls to the appropriate file system driver, ensuring seamless compatibility regardless of the actual file system in use.

Question 9

You have a Linux server with an unknown process listening on a network port. How do you work out which process is listening on the port?

Answer 9

1. netstat -nlp will show processes listening on ports
2. lsof -p PID will show all the files the process has open
3. strace -p PID shows what system calls a process is making
4. wireshark to show network traffic