Operating Systems MCQ Quiz - Objective Question with Answer for Operating Systems - Download Free PDF

​The correct answer is mkdir

Key Points

• mkdir: The 'mkdir' command is used to make directories in Linux and other Unix-like operating systems.
• The basic usage would be mkdir directoryname where 'directoryname' is the name of the directory you want to create.
• You can also make multiple directories at once and parent directories.
• For example, if you want to create a directory called "myfolder", you'd use:

       mkdir myfolder

Additional Information

• grep: The 'grep' command is used to search text. It searches the given file for lines containing a match to a specified pattern.
• Here's the basic syntax of grep: grep [options] pattern [files]
• For example, if you want to search for the word "error" in a log.txt file, you'd use:

       grep "error" log.txt

• pwd: The 'pwd' command is short for 'print working directory'.
• It's used to display the directory in which the user is currently working.
• Running the command does not need any options or variables, just pwd.
• For example, if you want to know your current directory, you'd use:

       pwd

• chmod: The 'chmod' command is used to change the permissions of files or directories.
• It comes from 'change mode', and it's used to define who can read, write, and execute a file. The basic usage is chmod options permissions file.
• For example, to give the user execute (the owner of the file) permissions for a file called "myfile", you'd use:

      chmod u+x myfile

The correct answer is is a method of memory allocation by which the program is subdivided into equal portions, or pages and core is subdivided into equal portions or blocks..

Key Points

• Paging is a memory management scheme that eliminates the need for contiguous allocation of physical memory.
• In paging, the operating system retrieves data from secondary storage in same-size blocks called pages.
• It divides the program into fixed-size pages and the main memory into blocks of the same size, called frames.
• When a program is to be executed, its pages are loaded into any available memory frames from the secondary storage.

Concept:

Scan Algorithm

It is also called as Elevator Algorithm. In this algorithm, the disk arm moves into a particular direction till the end, satisfying all the requests coming in its path,and then it turns backand moves in the reverse direction satisfying requests coming in its path.

Advantages 

1. This algorithm is simple and easy to understand.
2. SCAN algorithm have no starvation.
3. This algorithm is better than FCFS Scheduling algorithm .

Disadvantages 

1. More complex algorithm to implement.
2. This algorithm is not fair because it cause long waiting time for the cylinders just visited by the head.

Hence Option 2 is correct

Concept:

Dirty bit: Dirty bit is associated with a block of cache memory and it is used to show the page that is modified after being loaded into cache memory.

Explanation:

During write back police in cache, dirty bit concept is used.
Write back means updates are written only to the cache. When line is modified it’s dirty bit is set and when the line is selected for replacement, the line needs to be written to main memory only if it’s dirty bit is set.

In write back, we first write the cache copy to update the memory. Number of write backs can be reduced if we write only when cache data is different from memory. It is done by dirty bit or modifying bit. It writes back to the cache only when dirty bit is set to 1. Thus, write back cache requires two bits one is valid bit and another is dirty bit.

Diagram:

When a file in a Windows system is edited and closed without saving its contents, a dialog box will typically appear, asking the user whether they want to save the changes or discard them. The options provided may include "Save", "Don't Save", or "Cancel".

Note:

• If the user chooses "Save", the changes will be saved to the file and the file will be closed.
• If the user chooses "Don't Save", the changes will be discarded, and the file will be closed.
• If the user chooses "Cancel", the file will remain open and the user can choose to either save or discard the changes they made.

A utility program merges the records from two files into one for optimization purposes.

Following are some functions of a Utility software

→ to analyse a system

→ to configure various parts

→ to optimize the functionalities

→ to maintain a computer.

It is used to support the computer infrastructure in contrast to application software, which is aimed at directly performing tasks that benefit ordinary users.

The correct answer is option 2.

Concept:

The quality and loss of audio data are determined by the audio format. Many different audio formats are utilized, depending on the application.

The three categories of audio formats are as follows:

Lossy Compressed format:

Different types of lossy compressed formats are,

• ​PCM(Pulse-Code Modulation),
• WAV( Waveform Audio File Format) and
• AIFF(Audio Interchange File Format)

Uncompressed Format:

Different types of Uncompressed formats are,

• MP3( MPEG-1 Audio Layer 3),
• AAC (Advanced Audio Coding), and
• WMA(Windows Media Audio)

Lossless Compressed Format:

Different types of Lossless Compressed formats are,

• FLAC(Free Lossless Audio Codec),
• ALAC (Apple Lossless Audio Codec) 
• MID ( Musical Instrument Digital Interface)
• WMA(Windows Media Audio)

Explanation:

A RAR file is a type of compressed file that may hold one or more files and directories. Simply described, a Roshal Archive Compressed file is a different format for compressing files and archiving them. RAR files function similarly to ZIP files.

Hence the correct answer is .rar.

The correct option is (2)

Diskcopy

Key Points

• A track-by-track copy of one disc into another is done with diskcopy. The copy command copies a specified set of files; the chkdsk and format commands do not copy anything.
• The COPY command does exactly what it says on the tin: it copies the text or image you've chosen and stores it on your virtual clipboard until another "cut" or "copy" command replaces it.
• Ctrl + C and Ctrl + V are the shortcut keys for copying and pasting in Windows, respectively.
• The operating system changes the file name automatically if you paste a file into the same directory it was copied from since each file name must be distinct.

Additional InformationFormat:- The general design of a document or spreadsheet is referred to as format or document format. For instance, the alignment of text in many English papers is to the page's left.

Chkdsk:- Chkdsk generates a status report for each file system after examining disc space and disc use.

Virtual Memory in Operating System:

• A computer can address more memory than the amount physically installed on the system. This extra memory is actually called virtual memory and it is a section of a hard disk that's set up to emulate the computer's RAM.
• Virtual memory implements the translation of a program's address space to physical addresses.
• Virtual memory serves two purposes. First, it allows us to extend the use of physical memory by using the disk.
• Second, it allows us to have memory protection because each virtual address is translated into a physical address.

The correct answer is Ready queue

Key PointsProcess scheduling queue or simply process queue are

• Job queue: It is the queue that keeps all the processes in the system.
• Ready queue: It is the queue that keeps a set of all processes residing in main memory, ready and waiting to execute. A new process is always put in this queue.
• Device queues: It is the processes which are blocked due to unavailability of an I/O device constitute this queue.

∴ The answer is ready queue.

Concept:

Swapping is a technique of temporarily removing the inactive program from the memory of a system to allow space for other processes.

Explanation:

It moves the process from the main memory when it is blocked and deallocating the memory. This free memory is allocated to the other processes.  When a process is swapped out, its executable copy is copied to the secondary memory. When the process is swapped back into the available main memory, the executable image that was swapped out is copied into the new block allocated by the memory manager.

Diagram:

Important Points

The size of the ready queue doesn’t depend on the number of processes. A single processor system may have a large number of processes waiting in ready queue  

Additional Information   

Transition Diagram:

Important Points:

n CPUs → maximum n process in running state

A real-time operating system is an operating system intended to serve real-time applications that process data as it comes in, typically without buffer delays. A real-time system is a time-bound system which has well defined fixed time constraints.

Concept

Threads are sometimes called lightweight processes because they have their own stack but can access shared data. Because threads share the same address space as the process and other threads within the process, the operational cost of communication between the threads is low, which is an advantage. 

Important Points:

Multiple threads of the same process share other resources of process except register, stack and stack pointer. In particular, a process is generally considered to consist of a set of threads sharing an address space, heap, static data, code segments and file descriptors.

Thread of the same process doesn't share program counter (register), stack,  registers