What is an advantage of executing a process in background?
The most common reason to put a process in the background is to allow you to do something else interactively without waiting for the process to complete. At the... Read more »
‘Unix Interview Questions’ - KyaPoocha.com
What is major difference between the Historic Unix and the new BSD release of Unix System V in terms of Memory Management?
Historic Unix uses Swapping – entire process is transferred to the main memory from the swap device, whereas the Unix System V uses Demand Paging – only the... Read more »
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... Read more »
Is the Process before and after the swap are the same? Give reason.
Process before swapping is residing in the primary memory in its original form. The regions (text, data and stack) may not be occupied fully by the process, there... Read more »
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, process’s u-area, and Kernel stack are swapped out, theoretically. Practically, if the process’s u-area contains the... Read more »
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... Read more »
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... Read more »
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... Read more »
What do you mean by nice value?
Nice value is the value that controls {increments or decrements} the priority of the process. This value that is returned by the nice () system call. The equation... Read more »
How the Kernel handles the fork() system call in traditional Unix and in the System V Unix, while swapping?
Kernel in traditional Unix, makes the duplicate copy of the parent’s address space and attaches it to the child’s process, while swapping. Kernel in System V... Read more »
Difference between the fork() and vfork() system call?
During the fork() system call the Kernel makes a copy of the parent process’s address space and attaches it to the child process.But the vfork() system call do... Read more »
What are the phases of swapping a page from the memory?
Page stealer finds the page eligible for swapping and places the page number in the list of pages to be swapped. Kernel copies the page to a swap device when necessary... Read more »
In what way the Fault Handlers and the Interrupt handlers are different?
Fault handlers are also an interrupt handler with an exception that the interrupt handlers cannot sleep. Fault handlers sleep in the context of the process that... Read more »
What is validity fault?
If a process referring a page in the main memory whose valid bit is not set, it results in validity fault.The valid bit is not set for those pages:that are outside... Read more »
What does the swapping system do if it identifies the illegal page for swapping?
If the disk block descriptor does not contain any record of the faulted page, then this causes the attempted memory reference is invalid and the kernel sends a “Segmentation... Read more »
How the Kernel handles the copy on write bit of a page, when the bit is set?
In situations like, where the copy on write bit of a page is set and that page is shared by more than one process, the Kernel allocates new page and copies the content... Read more »
Is it possible to create new a file system in UNIX?
Use ‘su’ command. The system asks for password and when valid entry is made the user gains super user (admin) privileges. Read more »
How many prompts are available in a UNIX system?
Two prompts, PS1 (Primary Prompt), PS2 (Secondary Prompt). Read more »
What are shell variables?
Shell variables are special variables, a name-value pair created and maintained by the shell. Example: PATH, HOME, MAIL and TERM Read more »
What does the command “ $who | sort –logfile > newfile” do?
The input from a pipe can be combined with the input from a file . The trick is to use the special symbol “-“ (a hyphen) for those commands that recognize the... Read more »