8/13/2019 DOS INTERNAL & EXTERNAL COMMANDS

http://slidepdf.com/reader/full/dos-internal-external-commands 1/5

DOS (Disk Operating System) 

OPERATING SYSTEM 

An operating system is software or a set of programs, which provide the environment to a

user for the easy use of computer. 

DOS 

Disk Operating System is an operating system, which makes computer useable, it is a

 program that has to be loaded to initialize computer. The single user operating system used in

microcomputers is called DOS because it controls the storage of information and detail on

disks. 

Tasks for DOS, 

  To control input and output devices 

  To enable user to load and execute program 

  To maintain an orderly system of data on the disk  

DOS COMMANDS 

There are two types of DOS commands, 

  Internal Commands 

  External Commands 

DOS INTERNAL COMMANDS 

The internal DOS commands are those commands, which are loaded automatically during

 boot up process and are present in the computer memory. Internal commands (DOS disk is

not needed use any time except when you are in software package). 

1. CLS

 This command is used to clear the screen 

C:\>CLS  Enter. 

2. DATE

This command is used to check date it allows us to change the date. Enter the date in the

format mm-dd-yy. 

C:\>DATE  Enter  

8/13/2019 DOS INTERNAL & EXTERNAL COMMANDS

http://slidepdf.com/reader/full/dos-internal-external-commands 2/5

Enter again. 

3. TIME

This command is used to check current time it allows us to change time. 

To check the current time, 

Type TIME press Enter  

C:\>TIME  Enter  

To change time enter new time in the format of hh:mm:ss. 

Press Enter again. 

4. DIR (DISK INFORMATION REPORT) 

This command is used to see the list of files and directories it displays one directory or file

name per line including the file extention. It also displays the total number of files listed and

free space remaining on the disk. 

C:\>DIR   Enter  

This command can be used in different ways. 

C:\>DIR/P  Enter  

To display list of directories and files page by page. 

C:\>DIR/W  Enter  

To display list of directories and files widthwise.  

C:\>DIR/AA  Enter  

To display all files only. 

C:\>DIR/AD  Enter  

To display all directories only 

C:\>DIR/S  Enter  

To display all directories and sub-directories. 

C:\>DIR/L  Enter  

To display list of directories in small letters. 

8/13/2019 DOS INTERNAL & EXTERNAL COMMANDS

http://slidepdf.com/reader/full/dos-internal-external-commands 3/5

C:\>DIR/ON  Enter  

To display directories in alphabetical order. 

C:\>DIR/O-N  Enter  

To display directories in reverse alphabetical order. 

C:\>DIR *. *  Enter  

To see list of all files of all directories. 

C:\>DIR A*.* Enter  

To see list of files with names. 

5. COPY CON 

This command is used to create a new file. 

C:\>COPY CON filename Enter. 

After pressing Enter you have a new file now you can write your syntax and save file with

(Ctrl+Z). 

6. TYPE 

This command is used to display the contents of any txt file. 

C:\>TYPE Filename Enter  

7. DEL 

This command is used to delete file. 

C:\>DEL Filename Enter. 

8. MD

This command is used to make a new directory. 

C:\>MD directory name Enter  

e.g. 

C:\>CD WITSPIRIT  Enter  

C:\WITSPIRIT> 

For making sub-directory 

8/13/2019 DOS INTERNAL & EXTERNAL COMMANDS

http://slidepdf.com/reader/full/dos-internal-external-commands 4/5

C:\WITSPIRIT>MD ISLAMABAD  Enter  

9. CD 

This command is used to change current directory. 

C:\>CD Directory name Enter  

C:\>CD.. (Change to main directory) 

10. CHANGE DRIVE 

This command is used to change the current drive. 

C: Enter Changes to C drive. 

D: Enter Changes to D drive. 

11. RD 

This command is used to remove a directory. 

C:\>RD Directory name Enter  

DOS EXTERNAL COMMANDS 

These commands are not present in the computer’s memory but these exists as separate fileson the disk. Whenever you type an external command it is first loaded in the RAM and then

execute. 

1. TREE 

This command is used to Graphically display the path of each directory and sub-directory 

On the drive. 

C:\>TREE Directory name or drive Enter  

e.g. 

C:\>TREE C:  Enter  

It will show the directory structure. 

2. DELTREE 

This command is used to delete a directory completely with all its contents. 

C:\>DELTREE Directory name Enter. 

8/13/2019 DOS INTERNAL & EXTERNAL COMMANDS

http://slidepdf.com/reader/full/dos-internal-external-commands 5/5

3. UNDELETE 

This command is used to restore the last deleted file. 

C:\>UNDELETE Filename.ext Enter  

4. LABEL 

This command is used to display, create or change the label or name of disk.  

C:\>LABEL Enter  

5. CHKDSK  

This command is used to display a status report for a disk. 

C:\>CHKDSK C: Enter