Unix Interview Questions & Answers
Showing 10 of 53 questions | Page 3
Unix technical interview questions and answers are frequently asked in system administration, DevOps, backend development, and support engineering roles. Unix forms the base for Linux and macOS, so companies expect candidates to understand file permissions, commands, shell scripting, process management, filters, pipes, and environment variables. Interviews in TCS, Infosys, Wipro, Cognizant, Capgemini, and Accenture often include Unix questions during both technical rounds and written tests. This guide explains frequently asked Unix commands and concepts using simple language, making it easy for freshers and experienced candidates to prepare. You can also download Unix interview questions PDFs and practice mock commands for better preparation.
Showing 10 of 53 questions
21. What scheme does the Kernel in Unix System V follow while choosing a swap device among the multiple swap devices?
Kernel follows Round Robin scheme choosing a swap device among the multiple swap devices in Unix System V.
22. What is a Region?
A Region is a continuous area of a processs address space (such as text, data and stack). The kernel in a ‘Region Table that is local to the process maintains region. Regions are sharable among the process.
23. What are the events done by the Kernel after a process is being swapped out from the main memory?
When Kernel swaps the process out of the primary memory, it performs the following:
Kernel decrements the Reference Count of each region of the process. If the reference count becomes zero, swaps the region out of the main memory,
Kernel allocates the space for the swapping process in the swap device,
Kernel locks the other swapping process while the current swapping operation is going on,
The Kernel saves the swap address of the region in the region table.
24. What do you mean by u-area (user area) or u-block?
This contains the private data that is manipulated only by the Kernel. This is local to the Process, i.e. each process is allocated a u-area.
25. What are the entities that are swapped out of the main memory while swapping the process out of the main memory?
All memory space occupied by the process, processs u-area, and Kernel stack are swapped out, theoretically.Practically, if the processs u-area contains the Address Translation Tables for the process then Kernel implementations do not swap the u-area.
26. What is Fork swap?
fork() is a system call to create a child process. When the parent process calls fork() system call, the child process is created and if there is short of memory then the child process is sent to the read-to-run state in the swap device, and return to the user state without swapping the parent process. When the memory will be available the child process will be swapped into the main memory.
27. What is Expansion swap?
At the time when any process requires more memory than it is currently allocated, the Kernel performs Expansion swap. To do this Kernel reserves enough space in the swap device. Then the address translation mapping is adjusted for the new virtual address space but the physical memory is not allocated. At last Kernel swaps the process into the assigned space in the swap device. Later when the Kernel swaps the process into the main memory this assigns memory according to the new address translati
28. How the Swapper works?
The swapper is the only process that swaps the processes. The Swapper operates only in the Kernel mode and it does not uses System calls instead it uses internal Kernel functions for swapping. It is the archetype of all kernel process.
29. What are the processes that are not bothered by the swapper? Give Reason.
Zombie process: They do not take any up physical memory.
Processes locked in memories that are updating the region of the process.
Kernel swaps only the sleeping processes rather than the ‘ready-to-run processes, as they have the higher probability of being scheduled than the Sleeping processes.
30. What are the requirements for a swapper to work?
The swapper works on the highest scheduling priority. Firstly it will look for any sleeping process, if not found then it will look for the ready-to-run process for swapping. But the major requirement for the swapper to work the ready-to-run process must be core-resident for at least 2 seconds before swapping out. And for swapping in the process must have been resided in the swap device for at least 2 seconds. If the requirement is not satisfied then the swapper will go into the wait state on th