Practical 3


3. What is Operating System? Explain basic DOS commands.

An operating system (OS) is a software program that manages the hardware and software resources of a computer. The OS performs basic tasks, such as controlling and allocating memory, prioritizing the processing of instructions, controlling input and output devices, facilitating networking, and managing files.


During the booting process commands are automatically loaded into the computer’s memory. They are in fact included in the Command.com file. So these commands are executable immediately after getting the dos prompt.

A few internal commands are

  •          VER
  •          VOL
  •          DATE
  •          TIME
  •          CLS
  •          DIR
  •          MD
  •          CD
  •          PATH
  •          RD
  •          COPY CON
  •          TYPE
  •          COPY
  •          DEL
  •          REN


A command can be written in Capitals or Small letters also. They are executed from command prompt. When you type command on cmd prompt and press "Enter" internal commands execute immediately.

VER: - Every operating System has its own edition number or release or version number. The version number indicates which edition of operating system you are working on.
Syntax: VER
Example: C:\> Ver
Output:  Microsoft Windows [Version 6.1.7600]

VOL: - It is used to display volume label and serial number of the current drive
Syntax: Vol
Example: C:\> VOL

DATE: - It is used to display the current system date and prompt for entering new date.
Syntax: Date
Example: C:\> date

TIME: - Displays the current system Time and prompt for entering new time.
Syntax: Time
Example: C:\> Time

CLS: - It is used to Clear the screen.
Syntax: CLS
Example: C:\> CLS

DIR: - This command displays the list of directories and files with details like date of creation
            whether it is directory or file etc.

Syntax: DIR
Switches:
dir/p : To view page wise result along with it display label and serial no.
dir/w : Displays width wise result  of filenames and directories with details and along with it display label and serial no..
dir/b : Display only file and directory without any details.
dir/l : Display all the information in lower case letters.

Example:
DIR *.txt         Display all the files with extension .txt
DIR D???.*    Display all the files starting with D and having less than or equal to
                          four characters in the file name and any extension.
Here “?” And “*” are called “wild card character”. “*” Stand for any number of the character. “?” Stands for one character.
  
MD OR MKDIR:  Used to create a new Directory.
Syntax: MKDIR OR MD DIRECTORY NAME
Example: C :\> MD JAMS

CD OR CHDIR: - This command allows you to change present directory to another directory.
Syntax: CD
Example: C:\> CD JAMS

RD: - To delete the empty directory.
Syntax: RD
NOTE: -The directory must be empty when we use RD.
Example: C:\> RD JAMS
Switches: -
RD/s – Remove with subdirectories and files.
RD /q – Don’t ask to confirm.
  
COPY CON: This command is used to create a new file.
Syntax: COPY CON <FILENAME>
Example: C:\> Copy Con JAMS.txt
Note: - Type the content of the file here and when completed, press Ctr+Z or F6 key followed by Enter to save the current document.

TYPE: - This command is ude to see the contents of an existing file.
 SYNTAX: TYPE <file name>
Example: C :\> TYPE JAMS


COPY: - This command is used to copy an existing file from one location to another or one directory to another with different name or exiting name.

SYNTAX:        COPY < SOURCE FILE NAME>  <TARGET FILENAME>
Example:         C:\> COPY JAMS.TXT E:\SP
Example:         C :\> COPY JAMS.TXT C:\JAMS_new\Reena\TITHI
You can also have the option to change the name of files as you copy it.
Example: C :\> COPYold.TXT C:\dos\new.txt

DEL/ERASE: This command removes one or more files from the disk or current working directories.
SYNTAX: DEL filespec [/p] or ERASE filespec [/p]
Example: C:\> DEL abc
Switches:        
del /p  –confirmation
del/q – In quit mode

REN: Used to rename or change name of the file or directory.
SYNTAX: REN <file name> <new file name>
Example:  REN JAMS JAMS1

TREE: - It is used to display the tree structure of current directory graphically.
Syntax: TREE [drive:] [path] [/f]
[/F] : displays the names of the files in each directory.

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