Making Batch Files

A batch file is a regular text file (*.txt) except that it has been given a *.bat extension. It can be created with any ASCII text editor such as Notepad or the DOS Editor. You simply type DOS commands into the file, one command per line. When you run the batch file, the series of DOS commands will be executed as though the commands were typed at a DOS prompt in a Command window.

Basic DOS Commands:

REM

REM [comment]

Records comments (remarks) in a batch file.

COPY

Copies one or more files to another location.

COPY [/A | /B] source [/A | /B] [+ source [/A | /B] [+ ...]] [destination

[/A | /B]] [/V] [/Y | /-Y]

source Specifies the file or files to be copied.

/A Indicates an ASCII text file.

/B Indicates a binary file.

destination Specifies the directory and/or filename for the new file(s).

/V Verifies that new files are written correctly.

/Y Suppresses prompting to confirm you want to overwrite an

existing destination file.

/-Y Causes prompting to confirm you want to overwrite an

existing destination file.

The switch /Y may be preset in the COPYCMD environment variable.

This may be overridden with /-Y on the command line

To append files, specify a single file for destination, but multiple files

for source (using wildcards or file1+file2+file3 format).

MOVE

Moves files and renames files and directories.

To move one or more files:

MOVE [/Y | /-Y] [drive:][path]filename1[,...] destination

To rename a directory:

MOVE [/Y | /-Y] [drive:][path]dirname1 dirname2

[drive:][path]filename1 Specifies the location and name of the file

or files you want to move.

destination Specifies the new location of the file. Destination

can consist of a drive letter and colon, a directory

name, or a combination. If you are moving only one

file, you can also include a filename if you want

to rename the file when you move it.

[drive:][path]dirname1 Specifies the directory you want to rename.

dirname2 Specifies the new name of the directory.

/Y Suppresses prompting to confirm creation of a directory

or overwriting of the destination.

/-Y Causes prompting to confirm creation of a directory or

overwriting of the destination.

The switch /Y may be present in the COPYCMD environment variable.

This may be overridden with /-Y on the command line.

The MOVE command moves a file to a new location.

DEL

Deletes one or more files.

DEL [drive:][path]filename [/P]

ERASE [drive:][path]filename [/P]

[drive:][path]filename Specifies the file(s) to delete. Specify multiple

files by using wildcards.

/P Prompts for confirmation before deleting each file.

CLS

Clears the screen.

CLS

PAUSE

Suspends processing of a batch program and displays the message:

Press any key to continue....

PAUSE

ECHO

Displays messages, or turns command-echoing on or off.

ECHO [ON | OFF]

ECHO [message]

Type ECHO without parameters to display the current echo setting.

The @ symbol means don’t echo a line if echo is on. So, typing ECHO OFF prevents the user from watching the batch program execute and typing:

@echo off

will keep the user from seeing the ECHO OFF message. It is common for batch programs to start with the @ECHO OFF command followed by CLS. If you turn ECHO OFF in your batch program, be sure to put ECHO ON at the end of the program. Otherwise other DOS programs may not show important messages.

*To launch an executable from a batch file, simply enter the path of the executable, just like you would do at a command prompt. If you use a relative path, it will be relative to the directory that the batch file was launched from.

Using Command line Arguments:

Command line arguments are parameters which follow the program to be launched at the command prompt. For instance, lets say my batch file is called example.bat. At a command prompt, I might type:

Example.bat John Smith

Here, “John” is the first command line argument and “Smith” is the second. My Batch file then might appear as:

@echo off

cls

echo My first name is %1

echo My Last name is %2

pause

echo on

The %1 and %2 act as place holders for the command line arguments.

Program Control

Usually, commands in a batch file will execute sequentially. However, it is sometimes desirable to carry out commands in a different order. DOS has several programming structures which are similar to BASIC programming for manipulating your batch file.

GOTO

Directs Windows to a labelled line in a batch program.

GOTO label

label Specifies a text string used in the batch program as a label.

You type a label on a line by itself, beginning with a colon.

The GOTO command can be used to jump from one point in a program to another. It can be used as a simple method for skipping forward or backwards in your program. You need to place labels in your program to act as reference points. For example:

echo off

REM print COOL all over the screen

:start

echo COOL

goto start

echo on

“:start” is the label . This program will type COOL over and over again in an infinite loop until you stop the program by pressing CTRL + C.

FOR...IN...DO

Runs a specified command for each file in a set of files.

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

%variable Specifies a replaceable parameter.

(set) Specifies a set of one or more files. Wildcards may be used.

command Specifies the command to carry out for each file.

command-parameters

Specifies parameters or switches for the specified command.

To use the FOR command in a batch program, specify %%variable instead of

%variable.

The FOR statement does not have to be used with files, it can also be used with strings.

Example:

REM command that prints out a list of names

FOR %%a IN (Andy Bob Carl Darren Eric) DO echo %%a

The loop will execute the echo command 5 times because there are 5 items in the argument list. Notice how you can use the variable %%a as a substitute for each of the names.

IF

Performs conditional processing in batch programs.

IF [NOT] ERRORLEVEL number command

IF [NOT] string1==string2 command

IF [NOT] EXIST filename command

NOT Specifies that Windows should carry out the command only

if the condition is false.

ERRORLEVEL number Specifies a true condition if the last program run returned

an exit code equal to or greater than the number specified.

command Specifies the command to carry out if the condition is

met.

string1==string2 Specifies a true condition if the specified text strings

match.

EXIST filename Specifies a true condition if the specified filename

exists.

The IF statement will execute the “command” if the condition is TRUE. It can optionally be used with the NOT modifier to reverse the condition.

Example:

ECHO OFF

REM check whether a file called 'test.txt' exists

IF EXIST test.txt GOTO :success

IF NOT EXIST test.txt GOTO :error

:success

ECHO file test.txt exists

GOTO :end

:error

ECHO Error - can't find the test.txt file

GOTO :end

CHOICE

Waits for the user to choose one of a set of choices.

CHOICE [/C[:]choices] [/N] [/S] [/T[:]c,nn] [text]

/C[:]choices Specifies allowable keys. Default is YN

/N Do not display choices and ? at end of prompt string.

/S Treat choice keys as case sensitive.

/T[:]c,nn Default choice to c after nn seconds

text Prompt string to display

ERRORLEVEL is set to offset of key user presses in choices.

Example:

CHOICE/C:yn Do you want to install MyTest %1

IF ERRORLEVEL 2 GOTO :no

IF ERRORLEVEL 1 GOTO :yes

:yes

setup.exe

GOTO :end

:no

echo operation cancelled

:end

You can use the CHOICE statement with as many possible choices as you want.

CHOICE/C:abcd choose a letter

IF ERRORLEVEL 4 GOTO choice_d

IF ERRORLEVEL 3 GOTO choice_c

IF ERRORLEVEL 2 GOTO choice_b

IF ERRORLEVEL 1 GOTO choice_a

Much more can be done with DOS and batch files, but what is offered here should be sufficient for most basic installers. If you would like more information about creating batch files, consult a DOS manual.

*Note: Text written in italics was extracted directly from DOS help. For help with any DOS command, type /? after the command at a DOS prompt.