Disk Operating System (DOS) MCQ Questions & Answers | Computer Science

The Autoexec.bat file is the name of the batch file that is automatically run when MS-DOS is booted.

It stands for "automatic execution" and contains commands that DOS executes each time it starts up.
This file is used to set environment variables, run programs, and customize the DOS environment according to user preferences.
It is located in the root directory of the boot drive (typically C:) and is crucial for configuring the DOS environment.

Run.bat is not a standard batch file automatically run during MS-DOS boot-up; it would need to be explicitly invoked.

Config.sys is a system configuration file in DOS, but it is not automatically executed like Autoexec.bat.

Config.bat is not a standard DOS file and typically not used as a boot-up batch file.

Therefore, the correct answer is Option D: Autoexec.bat.

The /v switch is used with the copy command in DOS to verify that files are copied correctly.

When you use copy /v, DOS verifies each file after copying to ensure that it matches the original file.
This switch is useful for ensuring data integrity during file copying operations.
If any discrepancies are found during verification, DOS displays an error message.

/a switch is used with the copy command to copy files with the archive attribute set, but it does not verify the copy.

/c switch is not used with the copy command in DOS for verifying file copies.

/s switch is used with the copy command to copy directories and subdirectories, not for verifying file copies.

Therefore, the correct answer is Option D: /v.

The command prompt string $l$p$g typically represents:
$l stands for the current drive letter, which is usually C.
$p stands for the path separator, which is typically \.
$g stands for the command prompt symbol, which is usually >.

When you combine these components:
$l$p$g translates to C:\>.

Now, let's review the options provided:

Option A: - This format < > is not standard for representing the command prompt.
Option B: C:\> - This matches the expected output format of C:>, which is correct.
Option C: C:\>> - This includes an extra > which is not standard in DOS for the command prompt.
Option D: C:<\> - This format < > is not standard for representing the command prompt.

Therefore, upon reviewing again, Option B: C:\> is indeed the correct answer, representing the expected output of the command prompt string $l$p$g in a DOS environment.

Chkdsk (Check Disk) is the best tool among the options listed for fixing errors on disks in DOS.

Chkdsk is used to check the integrity of the file system and file system metadata on a disk.
It scans the disk for errors such as bad sectors, lost clusters, cross-linked files, and directory errors.
Chkdsk can fix certain types of errors it finds during its scan, helping to maintain the disk's health and data integrity.

Fdisk is a tool used for partitioning hard drives and creating partitions, not for fixing errors on disks.

Scandisk (ScanDisk) is an older tool similar to Chkdsk that checks and repairs file system errors and bad sectors.
While Scandisk is useful, Chkdsk is generally considered more robust and capable of handling a wider range of disk issues.

Fixdsk is not a standard DOS command or tool; it seems to be a variant or misspelling of the correct tool names.

Therefore, the correct answer is Option C: Chkdsk.

Format is the command used in DOS to create the disk's tracks and sectors.

When you format a disk using the format command, it prepares the disk by creating the necessary file system structures (tracks and sectors) for storing data.
It also marks bad sectors on the disk, if any, and initializes the disk for use.
The syntax for formatting a disk is typically format drive_letter: where drive_letter: is the letter of the drive you want to format (e.g., format C: for formatting the C drive).

Fdisk is used for partitioning a hard disk into one or more logical drives, not for creating the physical tracks and sectors.

Chkdsk is used to check the integrity of the file system and fix errors on a disk, not for creating disk tracks and sectors.

Attrib is used to change file attributes (like hidden or read-only), not for disk formatting.

Therefore, the correct answer is Option B: Format.

UNDELETE is the command in DOS that can be used to recover accidentally deleted files.

When files are deleted in DOS, they are often not immediately erased but rather marked as deleted in the file allocation table (FAT).
The UNDELETE command can sometimes recover these files by restoring the file entries in the directory structure, provided the clusters that held the file data have not been overwritten.
The syntax for using UNDELETE typically involves specifying the name of the file or files to be recovered.

DELETE/CANCEL is not a valid command in DOS for recovering deleted files; it suggests canceling a delete operation.

RESTORE is not a command in DOS for recovering deleted files; it is used in some backup systems to restore backed-up files.

RECOVER is also not a command in DOS for recovering deleted files; it typically refers to recovering data from damaged disks or partitions.

Therefore, the correct answer is Option A: UNDELETE.

VER is the command in DOS used to display the version of MSDOS.

When you type ver at the command prompt and press Enter, DOS displays the version number of the operating system currently running.
This command is useful for verifying the version of MSDOS installed on a system.
The version number typically includes major and minor version information, such as "MS-DOS Version 6.22".

VERSION is not a valid command in DOS for displaying the version; it's not recognized as a standard DOS command.

VERIFY is used to enable or disable file verification when files are written to a disk, not for displaying the DOS version.

VERSN is not a valid command in DOS; it seems to be a misspelling or non-existent command.

Therefore, the correct answer is Option C: VER.

Copy *.txt a: is the command used in DOS to copy all files with the extension .txt from drive A to the currently logged drive and directory.

The copy command in DOS is used to copy files from one location to another.
*.txt specifies that all files with the .txt extension should be copied.
a: indicates the source drive from where the files should be copied (drive A in this case).
The destination, which is not explicitly shown but assumed, is the currently logged drive and directory.

Copy a. *.txt is not a valid syntax in DOS for copying files; it has incorrect placement of the source and destination.

Copy *.txt c: would copy .txt files to drive C, not to the currently logged drive and directory.

Copy *.txt all.txt would attempt to copy all .txt files into a single file named "all.txt", which is not the same as copying to the currently logged directory.

Therefore, the correct answer is Option B: Copy *.txt a:.

Format is the command used in DOS to create the root directory and File Allocation Table (FAT) on a disk.

When you format a disk using the format command, it prepares the disk by creating the necessary file system structures, including the root directory and the FAT.
The root directory is the top-level directory of a disk, where other directories and files are stored.
The FAT is a table that DOS uses to keep track of the status of each cluster on the disk (whether it is free or allocated to a file).
The syntax for formatting a disk typically involves specifying the drive letter followed by the colon (e.g., format C: for formatting the C drive).

Chkdsk is used to check the integrity of the file system and to fix errors on a disk, but it does not create the root directory or the FAT.

Command.com is the system file that contains the DOS command interpreter, not a command used for disk formatting.

Fat is not a command in DOS; it refers to the File Allocation Table itself, not a command to create it.

Therefore, the correct answer is Option C: Format.

Del *.txt is the command used in DOS to delete all files with the extension .txt from the current drive and directory.

The del command in DOS is used to delete files.
*.txt specifies that all files with the .txt extension should be deleted.
When you execute del *.txt at the command prompt, DOS will delete all files ending with .txt in the current directory.

Del .txt is not the correct syntax for deleting files with a specific extension; it would attempt to delete a file named ".txt".

Erase .txt is not a valid command in DOS for deleting files; the correct command is del instead of erase for file deletion.

Del . /p is incorrect because the /p switch is not used for deleting files. It typically stands for prompting before deleting, but it's not part of the standard del command syntax.

Therefore, the correct answer is Option C: Del *.txt.