Explain kill() and its possible return values.
There are four possible results from this call: ‘kill()’ returns 0. This implies that a process exists with the given PID, and the system would allow you to... Read more »
‘Unix Interview Questions’ - KyaPoocha.com
How to terminate a process which is running and the specialty on command kill 0?
With the help of kill command we can terminate the process. Syntax: kill pid Kill 0 - kills all processes in your system except the login shell. Read more »
Is ‘du’ a command? If so, what is its use?
Yes, it stands for ‘disk usage’. With the help of this command you can find the disk capacity and free space of the disk. Read more »
What is the significance of the “tee” command?
It reads the standard input and sends it to the standard output while redirecting a copy of what it has read to the file specified by the user. Read more »
What difference between cmp and diff commands?
cmp - Compares two files byte by byte and displays the first mismatch diff - tells the changes to be made to make the files identical Read more »
What is the use of ‘grep’ command?
‘grep’ is a pattern search command. It searches for the pattern, specified in the command line with appropriate option, in a file(s). Syntax : grep Example :... Read more »
What is a Make File?
Make file is a utility in Unix to help compile large programs. It helps by only compiling the portion of the program that has been changed. Read more »
Explain the layered aspect of a UNIX system. What are the layers? What does it mean to say they are layers?
A UNIX system has essentially three main layers: . The hardware . The operating system kernel . The user-level programs The kernel hides the system’s hardware... Read more »
How do you change File Access Permissions?
Every file has following attributes: owner’s user ID ( 16 bit integer ) owner’s group ID ( 16 bit integer ) File access mode word ‘r w x -r w x- r w x’ (user... Read more »
List the system calls used for process management:
System calls Description fork() To create a new process exec() To execute a new program... Read more »
What is the difference between Swapping and Paging
Swapping: Whole process is moved from the swap device to the main memory for execution. Process size must be less than or equal to the available main memory. It... Read more »
What is the main goal of the Memory Management?
It decides which process should reside in the main memory, Manages the parts of the virtual address space of a process which is non-core resident, Monitors the available... Read more »
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. Read more »
What is a Region?
A Region is a continuous area of a process’s address space (such as text, data and stack). The kernel in a ‘Region Table’ that is local to the process maintains... Read more »
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. Read more »
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... Read more »
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... Read more »
What are conditions on which deadlock can occur while swapping the processes?
All processes in the main memory are asleep. All ‘ready-to-run’ processes are swapped out. There is no space in the swap device for the new incoming process... Read more »
What are conditions for a machine to support Demand Paging?
Memory architecture must based on Pages, The machine must support the ‘restartable’ instructions. Read more »
What is ‘the principle of locality’?
It’s the nature of the processes that they refer only to the small subset of the total data space of the process. i.e. the process frequently calls the same subroutines... Read more »