internal commands.29to30

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Internal commands


Objective

On completion of this period, you would be able On completion of this period, you would be able to knowto know

Conventions usedConventions used

Internal commands Internal commands


Recap

DOS commands are divided into

Internal Commands

External Commands


Prerequisite

What is meant by command

An instruction which is used to communicate with a computer system

We call this instruction a command


Internal Commands

Internal commands are built–in commands

These commands are in COMMAND.COM program

This program is loaded with the operating system into the memory during booting


Internal Commands (contd)

Remains resident in the memory as long as the computer is on

Hence they are always available to be executed


Convention used in Command descriptions are

[] (BRACKETS)Items within brackets are optional

DRIVE It refers to the drive name. Example: C: A: B: etc


Convention used in Command descriptions are (contd)

PATHIt refers to a directory nameSyntax :[\drive_directory] [\directory…]\ directory

PATHNAMEIt mentions the files that are to be referred in the path. It is used to locate a fileSyntax : [\drive_directory] [\directory…] \filename



SWITCHES

These switches control MS – DOS commands. They should always begin with a forward slash (/)

Example: /p /w etc



WILDCARDS

If we want to carry out a task for a group of files whose names have something in common, we can use wildcard characters to specify groups of files


Wild characters DOS recognizes two wildcard characters

Asterisk(*) – represents one or more characters that a group of files has in common

Question mark(?) – represents a single character that a group of files has in common


Examples of wildcards

*.txt : All files with .txt extension Examples are letter.txt, july.txt, and message.txt

report.* - All files named report with any extension.Examples: report.txt, report.let and report.wri.


Examples of wildcards (contd)

M*.* : All files beginning with the letter M regardless of extension.Example are march.xls, memo.txt and madhavi.lvu

???.* : all files having 3 or less characters with or without any extensions.Examples are sun.bmp, son.bm and ab.x


Internal Commands

CLS- Clears the screen, takes the cursor to the top left and the system Prompt appears at top left

VER – It displays the MS-DOS version

DEL/ERASE [drive:] pathname – It deletes the specified file or files. The wildcards (* and ?) can be used with del command to delete more than one file at a time



VOL [drive] – It displays the disk volume label which is optionally declared at the time of formatting

Example:C:\>VOL A :

ResultVolume in drive A is DBASEIIIVolume Serial Number is 0909-07BE



PROMPT [[text] [$character]…] – It changes the MS-DOS command prompt. $ character prompts are below

$t Current time $l <$d Current date $q =$n Drive letter $$ $$p Directory $e Escape$v Version number $g > $h Backspace$_ Return-Linefeed



DATE [mm- dd- yy] - It displays or sets the date

Example:C>DATE

Result:Current date is FRI 21-04-07Enter the new date (mm- dd- yy): 20-04-08Now the current date will be SUN 20-04-08



TIME [hours : minutes : seconds . Hundredths]

It allows to enter or change the time of the system and see the current time

To type a new time, the valid values are hours is 0-23, minutes is 0-59, seconds is 0-59 and hundredths of seconds 0-99



Example1 C>TIME

ResultCurrent time is 1:28:40.51Enter the new time : 11:07:51.21Now the current time will be ’11:07:51.21



Example2 C>TIME 12:07:59C>TIME

ResultCurrent time is 12:07:59Enter the new time :



PATH [drive:] [path] [;[drive:] [path]…]

It sets a command search path for programs not in the current directory

The above command is used to search more than one path by specifying several paths separated by semicolons



DIR [drive:] [pathname] [/p] [/w] – To list the files in a directory. Wildcards can also be used with Dir command

Example1C>DIR

ResultVolume in drive C is DOS400



Directory of C:\vinay. <dir> 1-11-90 1:05.. <dir> 1-09-90 13:05BASIC EXE 67520 19-12-90 2:13BUDGET BAS 814 1-01-91 1:45FINAN90 BAS 3456 7-07-90 7:34 5 File (s) 4329472 bytes free



Example2C>DIR/W

ResultSelects wide display and lists up to files lines per line



Example3 C>DIR/P

Result Selects page mode and makes the

directory display to pause once the screen is filled

To resume scrolling the display any key can be pressed



TYPE [drive] filename – It displays the contents of a text file on the screen

Example:C>TYPE message.dat>PRN

ResultIt sends the contents of file “message.dat”

to the printer



COPY [drive:] [pathname] [drive:] [pathnamr2] – It copies one or more files to another location

COPY pathname1 + pathname2 […]pathname.. It appends the files. Wildcards can also be used with copy command



Example1C>copy bpay.rpt basicpay.rpt

Result It copies a file named ‘bpay.rpt’ in the

same drive asanother name called ‘basicpay.rpt’



Example2C>copy BPAY.RPT A:PROLL.RPT

Result It copies a file bpay.rpt from current drive

C to drive A named as proll.rpt



Example3 C>COPY *.rpt + ref.txt summary.doc

Resultthe above copy command combines all

*.rpt files and ref.txt files and stores in filename called summary.doc



MKDIR/MD [drive:] path – This command creates required directory

ExampleC>MKDIR letters

ResultIt the above example, the command is

used to create a directory named letters



CHDIR/CD [path] – It changes the current directory for the specified directory

Example C>CHDIR division

ResultThe above command changes the working

directory to the directory called ‘division’


Internal Commands (contd) RMDIR/RD [drive:] path – It removes a directory

from a directory structure

ExampleC>RMDIR varsham

ResultThe above command is used to remove

the directory named varshamBefore removing the directory entirely, the

directory should be empty.


Summary

In this class, we have learnt about

Internal commands – COPY, DEL, DIR, TYPE, CD, MD, RD, MODE, PATH, DATE, TIME, COPY CON etc.


Frequently Asked Questions

1. List any four DOS internal commands

2. What is DOS internal command?

3. Explain any four internal commands in DOS.


Quiz

Internal commands are _________Answer: built in commands


Quiz

The instructions which are used to communicate with the computer systema. instructionsb. commands

Answer: b

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internal commands.29to30

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