Advanced Batch Files

Ch 11 1

Advanced Batch Files

Ch 11 2

OverviewOverview

Quick review of batch file commands learned in earlier

chapters.

Ch 11 3

OverviewOverview

Advanced features of these commands will be explained

and used.

Ch 11 4

OverviewOverview

Will explain the purpose and function of remaining batch file commands

and then will use these commands to write sophisticated batch files.

Ch 11 5

OverviewOverview

Will refine techniques in working with environment.

Ch 11 6

Batch File CommandsBatch File Commands

Batch files: Have file extension .BAT or .CMD Are ASCII text files Include legitimate commands Create generic batch files using

replaceable parameters Are not case sensitive

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Any command used at the command line can be used in a

batch file.

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Batch File CommandsBatch File CommandsTable 11.1 Batch File Commands p. 548Table 11.1 Batch File Commands p. 548

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Batch File CommandsBatch File CommandsTable 11.1 Batch File Commands p. 548Table 11.1 Batch File Commands p. 548

Ch 11 10


Batch files have: Limited vocabulary (commands) Syntax Programming logic

Ch 11 11

Review of REM, PAUSE, Review of REM, PAUSE, and ECHO Commandsand ECHO Commands

REM command (remarks): Documents batch file Not a command that executes With ECHO ON displays but does not

execute what follows REM Placed at beginning of a line in batch

or CONFIG.SYS file, REM disables but does not delete line

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PAUSE command: Instructs batch file to stop executing

until user takes some action Does not stop execution of .EXE or

COM program

Will not do any conditional processing

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To interrupt a batch file during execution:

Press <Ctrl> + C Press <Ctrl> + <Break>

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ECHO command: Used on command line or in

batch file Controls printing of messages on

screen when batch file run

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ECHO ON -displays all commands to screen along with output.

ECHO OFF - displays only output of commands to the screen.

Precede ECHO OFF with @ and “ECHO OFF” will not appear on screen.

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Advanced Features of Advanced Features of ECHO and REMECHO and REM

For faster processing, use a double colon (::) instead of

“REM” in front of remark or documentation line.

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To delete the display of even the message “1 file(s) copied”, redirect output of command to

NUL device.

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Using NUL will not suppress a message such as “file not

found”.

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There is no such thing as a blank line in batch files.

Pressing <Enter> does not generate a blank line in batch files.

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To insert a blank line, key in ECHO followed by a period

(ECHO.)

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Activity—Using ECHO Activity—Using ECHO and NULand NUL

KEY CONCEPTS: Replaced REM with (::) for faster processing Redirected output to NUL device so no

messages/remarks shown on screen @ before ECHO OFF - “ECHO OFF” does

not appear on screen ECHO. created a blank line in batch file

Ch 11 22

The GOTO CommandThe GOTO Command

GOTO command: In conjunction with a label creates a

loop Processes command following label

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Loop repeats steps until stopped by . . . using an IF statement. breaking into the batch file with

<Ctrl> + C.

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Label in a batch file: Is not a command Identifies location in a batch file Is preceded by a colon (:) No longer then 8 characters Not case sensitive Ignored by OS until called with GOTO command

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GOTO has one parameter: GOTO label

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Activity—Using the Activity—Using the GOTO CommandGOTO Command

KEY CONCEPTS: Debug - see and repair any errors To execute a batch file must be at

system prompt (not in editor) Usefulness of loops Redirecting output to NUL device

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Activity—Using the Activity—Using the GOTO CommandGOTO Command Example of a Batch file to delete

all files from many floppy disks@ECHO OFF:TOPCLSECHO Place disk with files no longer want in ECHO Drive A.PAUSEDEL /Q A:*.*\ECHO Press Ctrl + C to stop executing this batch file.ECHO otherwise, press any key to continue deleting files.PAUSE > NULGOTOTOP

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The SHIFT CommandThe SHIFT Command

SHIFT command allows for an unlimited number of

parameters on the command line.

Ch 11 29

Activity—Using the Activity—Using the Shift CommandShift Command

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KEY CONCEPTS: Can keep date log not dependent on file

modification date Usefulness of SHIFT command

Displays 5 or more parameters and places echoing parameters in batch file

Moves each parameter over by one position ECHO - echoes what is keyed in

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KEY CONCEPTS: + sign tells OS to concatenate files Contents of file ended when see EOF

Typically <Ctrl> + Z COPY command places second <Ctrl> + Z at

end of file creates problem Solve by copying file in binary mode

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KEY CONCEPTS: + /B switch - tells OS to copy file in binary

mode Concatenated files with no switches - files

copied in text mode >> used to see both name of directory and

bytes in directory. <Ctrl> + C used to “break out”

Ch 11 36

The IF CommandThe IF Command

IF command allows for conditional processing of parts of a batch file.

Conditional processing compares two items to determine if they are identical.

Ch 11 37

The IF CommandThe IF CommandResults of comparison testing: True

Items are identical Command executed

False Items are not identical Command not executed Goes to next command line in batch file

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The IF CommandThe IF Command

IF command checks to see: If two sets of characters are/are not identical If a file exists The value of the variable in ERRORLEVEL

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The IF CommandThe IF CommandIF command syntax :

IF <condition> <command>

IF [NOT] ERRORLEVEL number command IF [NOT] string1==string2 command IF [NOT] EXIST filename command

Note: complete syntax in Appendix H

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The IF Command The IF Command Using StringsUsing Strings

IF can be used to compare strings.

Two equal signs (= = ) separate items to be compared.

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The IF Command The IF Command Using StringsUsing Strings

Can tell IF statement to GOTO a label or to perform an operation whether the

condition is true or false.

Ch 11 42

Activity—Using the IF Activity—Using the IF Command with StringsCommand with Strings

KEY CONCEPTS: No more lines - return to system prompt Batch file replaceable parameters get value

from position on command line Case matters To ignore case add the /I parameter

immediately following the IF statement

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Testing for NULL ValuesTesting for NULL Values

If SHIFT used in a batch file will be caught in endless loop when all parameters are used.

Ch 11 44


A null value (value equal to “nothing”) must be placed in a batch file to indicate end of

data.

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Can test for a NULL value using IF with quotation marks.

IF “%1” = = GOTO LABEL

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Can test for a NULL value using IF with any word.

IF %1word = = word GOTO LABEL

word==word

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Can test for a NULL value using IF with backslash.

IF \%1\= =\\ GOTO LABEL

\\==\\

Ch 11 48

Activity—Using Activity—Using NULL ValuesNULL Values

KEY CONCEPTS: Test for a null value using

quotation marks Test for null value using a user

designated word

Ch 11 49

The IF EXIST/IF NOT The IF EXIST/IF NOT EXIST CommandEXIST Command

IF EXIST/IF NOT EXIST command: Checks for the existence or non-

existence of a file Works only with file names - not

directory names

Ch 11 50


Using IF EXIST command: If file does exist

Condition - true Processing passes to specified GOTO location

If file does not exist Condition - false Batch file reads next line in file

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Using IF NOT EXIST command: If file does not exist

Condition - true Processing passes to specified GOTO location

If file does exist Condition -false Batch file reads next line in file

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Activity—Using IF EXIST Activity—Using IF EXIST to Test for a Fileto Test for a File

1. IF \%1\= =\\ GOTO end

2. IF NOT \%2\= =\\ GOTO next

3. ECHO You must include a destination name

4. ECHO for the new directory name.

5. GOTO end

6. :next

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7. IF EXIST % 1 GOTO message

8. REN % 1 % 2

9. GOTO end

10. :message

11. ECHO This is a file, not a directory.

12. :end

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KEY CONCEPTS: IF command testing for true condition

True condition - command processed False condition - command ignored - next line in batch

file processed IF NOT command testing for “truth” in reverse

False condition - command processed True condition - command ignored - next line in batch

file processed

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KEY CONCEPTS: IF EXIST

Used to check for existence of a file Can not be used to check for existence of a

directory Use NUL to “fool” IF EXIST/IF NOT

EXIST to check for existence of directory

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The IF ERRORLEVEL The IF ERRORLEVEL Command TestingCommand Testing

Program can set an exit code when it finishes executing.

Batch file tests exit code with IF ERRORLEVEL statement.

Ch 11 57


An exit code is tested with ERRORLEVEL to determine if it is greater than or equal to it.

Ch 11 58


Exit codes listed in descending order when using IF ERROR LEVEL.

Exit codes listed in ascending order when using IF NOT ERORLEVEL.

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Activity—Using Activity—Using IF IF ERRORLEVELERRORLEVEL with COPY with COPY

KEY CONCEPT: User exit codes successfully in a

batch file

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Writing Programs to Test Writing Programs to Test for Key Codesfor Key Codes

Exit codes: Set by an operating system

program Created by writing small program

based upon an activity

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Every time a key is pressed, it is identified by a scan code.

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Can write programs by using: Programming language DEBUG (operating system

utility program)

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Easiest way to use DEBUG is to create a script file.

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A script file is set of instructions that can be written

in any text editor.

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Feed script file via redirection into DEBUG program.

DEBUG program converts script file to executable program with .com file extension.

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Summary of command available within BUG program (p. 576)

assemble A (Address)compare C range addressdump D (range)enter E address (list)fill F range listgo G [=address] [addresses]hex H value1 value2input I portload L [address] [drive] [firstsector] [number]move M range addressname N [pathname] [arglist]output O port byte

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Summary of command available within BUG program (p. 576)

proceed P [=address][number]quit Qregister R [register]search S range listtrace T [=address] [value]unassemble U [range]write W {address] [drive] [firstsector] [number]

allocate expanded memory XA [#pages]deallocate expanded memory XD [handle]map expanded memory pages XM [Lpage] [Ppage] [handle]display expanded memory status XS

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.COM Program Written with DEBUG to return scan code of Pressed Key

A:\>DEBUG-a 100 <Enter> 158E:0100 mov ah,8 <Enter>158E:0102 int 21 <Enter>158E:0104 cmp al,0 <Enter>158E:0106 jnz 10a <Enter>158E:0108 mov ah,8int21 <Enter>158E:010A mov ah,4c <Enter>158E:010C int 21 <Enter>158E:010E mov ah,8 <Enter>-r cx <Enter>CX 0000:e <Enter>-n reply.com <Enter>-w <Enter>Writing 000E bytes-q <Enter> <Enter>

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Easier way to create reply.com is to create script file with any text editorScript file - text file containing series of

commands that can be redirected into DEBUG to create a .COM file

Script file is not the program

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Activity—Writing a Activity—Writing a Script FileScript File

KEY CONCEPTS: Convert script file into a program by

redirecting it to DEBUG Error codes tested for equal to or greater than

value specified IF ERRORLEVEL - descending order IF NOT ERROR LEVEL - ascending order

Ch 11 71

The EnvironmentThe Environment

The environment is an area in memory where data can be

stored.

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Data: Constant/fixed values - never change Variables that do change - depends on

conditions or information passed to program

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In programming, an expression is any legal

combination of symbols that represent a value.

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The operating system stores data in form of two strings:

Name of variable Value of variable

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Environmental variable is name assigned to string (value) of

data.

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User can set environmental variables.

Some common variables set when Windows started.

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User can leave messages in environment using SET

command.

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Environmental variables set in Command Prompt window or batch files executed in Command Prompt

window remain in effect only during that command prompt session.

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SET syntax:

SET [ variable = [string] ]

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SET without parameters displays current

environmental variables.

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Activity—Using SET and the Activity—Using SET and the Environmental VariablesEnvironmental Variables

KEY CONCEPTS: Command processor must be in memory

when keying in command Using MORE

Pressing <Enter> - moves one line at a time Pressing <SpaceBar> - goes to end of file

SET with letter of alphabet - environmental variables beginning with letter displayed

Ch 11 82

Activity—Using SET and the Activity—Using SET and the Environmental VariablesEnvironmental Variables

KEY CONCEPTS: To see value of environmental variable - use

ECHO and enclose environmental variable name you are seeking with percent signs

Environmental variable Can be used with commands Can be used to change directories

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Using SET and the Using SET and the Environment in Batch FilesEnvironment in Batch Files

Can use built-in environmental variables that Windows sets and uses.

Can set own environmental variables.

Ch 11 84

Using SET and the Using SET and the Environment in Batch FilesEnvironment in Batch Files

Setting environmental variables: Can give them name and value in batch

file/command line Only good for that session of Command

Prompt Window

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Activity—Using SET and the Activity—Using SET and the Environment in Batch FilesEnvironment in Batch Files

KEY CONCEPTS: Can set environmental value and use it in batch file Environmental variables set - deleted when

Command Prompt window closed Environmental variables - not case sensitive To eliminate value - must set it at nothing Can add directory to PATH statement

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The DIRCMD The DIRCMD Environmental VariableEnvironmental Variable

DIRCMD environmental variable with: SET to preset DIR command parameters or

switches. ERRORLEVEL to change the way DIR

displays information for current MS-DOS work session.

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Activity—Using Activity—Using DIRCMDDIRCMD

KEY CONCEPTS: Can determine how to display batch

files Files displayed this way until change

values or close Command Prompt session

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FOR…IN…DO CommandFOR…IN…DO Command

FOR..IN..DO command: Allows repetitive processing Can be

issued at the command line placed in a batch file

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FOR allows the use of a single command to issue several commands at once.

Command can DO something FOR every value IN a specified set.

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Syntax at command line:

FOR %variable IN (set) DOcommand [command-parameters]

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Syntax in a batch program:

FOR %%variable IN (set) DOcommand [command-parameters]

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GOTO loop is vertical.

FOR…IN…DO loop is horizontal.

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There is a difference between a variable and a parameter.

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Activity—Using the Activity—Using the FOR…IN…DO CommandFOR…IN…DO Command

KEY CONCEPTS: Space and comma between items in a set work

same way Advantages of using space and comma between items

in a set Command line is case sensitive Variable letter chosen is not important % - used at command line %% used in batch file

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Activity—Using the FOR…Activity—Using the FOR…IN…DO CommandIN…DO Command

KEY CONCEPTS: Items in set is a horizontal not vertical loop Moved all batch files to BATCH subdirectory and

set path to include BATCH directory Caution: If close Command Prompt window, have

to issue following command to include the A:\BATCH directory in your path: A:\BATCH>A:\BATCH\ADD A:\BATCH

Changed dates of files

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More Features of the More Features of the FOR…IN…DO CommandFOR…IN…DO Command

New features of FOR…IN…DO command: May list environmental variables so they are

divided and appear on separate lines Use /R parameter (recursive parameter)

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More Features of the FOR…More Features of the FOR…IN…DO CommandIN…DO Command

New features of FOR…IN…DO command: Use tilde operator (~) to:

Strip a file name of quotation marks Expand variable

Select specific text from ASCII files

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KEY CONCEPTS: Use FOR…IN…DO to display list one line

at a time (list easier to read) Tilde (~) strips file name of quotation marks Use quotation marks to add prefix or suffix

to long file name REN only needs file name

Activity—Using Additional Activity—Using Additional Features of FOR…IN…DO Features of FOR…IN…DO

CommandCommand

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Activity—Using Additional Activity—Using Additional Features of FOR…IN…DO Features of FOR…IN…DO

CommandCommand

KEY CONCEPTS: Use n and x to precede any file name with

prefix Can strip out specific fields in a text file -

use /F parameter Can delimit data

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The CALL CommandThe CALL Command

CALL command: Allows you to run one batch file from

within another Returns control to original batch file

when second batch file is finished executing

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Activity—Using CALLActivity—Using CALL

KEY CONCEPTS: Use <Ctrl> + L - to eject a page Use <Ctrl> + G - to create a noise Create series of batch files that return to

directory you were previously in When executing a program within a batch

file - not returned to batch file unless you use CALL

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Activity—Using CALLActivity—Using CALL

KEY CONCEPTS:Creating and Saving batch file called HOMETO.BAT in BATCH directory

Line 1: COPY A:\BATCH\HOME.DAT A:\BATCH\HOMESAVE.BAT <Enter>

Line 2: CD >> A:\BATCH\HOMESAVE.BAT <Enter>Line 3:CALL HOMNESAVE.BAT <Enter>Line 4: DEL A:\BATCH\HOMESAVE.BAT <Enter>

Advanced Batch Files

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