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Mar 22, 2008

DOS - Script Snippets

DOS Batch Script Snippets.

Initializing a batch
Commands that are typically executed at the beginning of a batch script.
Version History
Add a version history, track date, author and description of each change.
Window Title
Change the Window Title.
Window Color
Change the Window Color.
Window Size
Change the Window Size.
Exit
Exit on key pressed.
Exit
Exit on key pressed with customized message.
Exit Delayed
Delayed exit without user interaction.
Echo Empty Line
How to use ECHO to output an empty line.
Multiple Commands in Single Line
How to enter multiple commands into a single line.
Multiple Lines for Single Command
How to continue a command in the next line.
Escape Characters
Escaping special characters in DOS batch when delayed variable expansion is enabled or disabled.
Command Grouping
Grouping Commands in blocks using Parentesis.
Conditional Execution
Conditional Execution Based on Result of Previous Command.
Open the Registry Editor at a given Key
Opening the Registry Editor at a defined Key.
RunAs Administrator
Force a batch to run as different user via RunAs command.
Does String1 begin with String2?
Check if one string starts with another.
Date Time for Unique String
Create a unique string using current date and time.
File Line Count
Use FIND command to count file lines, store line count into a variable.
File Size in Bytes
Use FOR command to determine the file size in bytes.
Check File for Zero Bytes
Use FOR command to show or delete empty files.
Unicode to Ansi
Convert a file to Ansi.
Ansi to Unicode
Use FOR command to show or delete empty files.
Drive Types
List all drives connected and corresponding types, i.e. Fixed, CD-ROM, Removable.
SET /A
Basic Integer Arithmetic.
Floating Point Arithmetic
Working around the limitations if the command processor.
Percent
Basic Percent arithmetic.
Large Integers
Working around the limitations if the command processor.
TOP
2008-03-07

Initializing a batch - Commands that are typically executed at the beginning of a batch script

Description:
At the beginning of a DOS batch file belongs the initialization of the command processor. This is to ensure subsequent DOS batch script will be handled by the command interpreter as we intended to. First let`s turn command-echoing off so that the output screen doesn`t get polluted with batch file content itself during execution. Second, in order to enable the great features of the command processor as required by most the other script code described here, the initialization code shall turn on Extensions and Delayed Expansion.
Script:
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 @echo off
REM.-- Prepare the Command Processor --
SETLOCAL ENABLEEXTENSIONS
SETLOCAL ENABLEDELAYEDEXPANSION
TOP
2008-03-07

Version History - Add a version history, track date, author and description of each change

Description:
Having a version history within you DOS batch file is good practice in order to keep track of when changed what. Have the following code block close to the beginning of each batch file to present a nicely formatted version history. The version history can be updated by copying the last entry and modifying Date, Author, and Description appropriately.
Script:
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 ::: -- Version History –-
:::          XX.XXX         YYYYMMDD Author Description
SET "version=01.000-beta" &:20051201 p.h.   initial version, providing the framework
SET "version=01.000"      &:20051202 p.h.   framework ready
SET "version=01.001"      &:20051203 p.h.   added cool new features
::: !! For a new version entry, copy the last entry down and modify Date, Author and Description
TOP
2008-03-07

Window Title - Change the Window Title

Description:
Application name and version of you application seem to make just the right title for the application window. Let`s store the title into a variable that way it can be reused later in the batch script in case we use the window title temporary to display something else. The TITLE command will set the window title.
Script:
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 ::: -- Set the window title --
SET "title=%~nx0 - version %version%"
TITLE %title%
TOP
2008-03-07

Window Color - Change the Window Color

Description:
The background and foreground color of a window can be changed using the COLOR command followed by TWO hex digits:
1st – background
2nd – foreground
The change will appear instantly for the whole window.
The color codes are:
    0 = Black       8 = Gray
    1 = Blue        9 = Light Blue
    2 = Green       A = Light Green
    3 = Aqua        B = Light Aqua
    4 = Red         C = Light Red
    5 = Purple      D = Light Purple
    6 = Yellow      E = Light Yellow
    7 = White       F = Bright White

Script:
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 ::: -- Set the window color --
COLOR 1A
TOP
2008-03-07

Window Size - Change the Window Size

Description:
To control the size of a window use the MODE command. The example shows how to size a window 90 characters horizontal and 10 lines vertical.
Script:
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 ::: -- Set the window size --
MODE CON: COLS=90 LINES=10
TOP
2008-03-07

Exit - Exit on key pressed

Description:
GOTO:EOF command will end a DOS batch application no matter whether subsequent code follow. Adding a PAUSE command will allow the user to inspect screen outputs before the application window disappears. Forcing an empty line via ECHO will nicely separate the "Press any key to continue" message created by the PAUSE command from any previous output.
Script:
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 ::: -- End of application --
ECHO.&PAUSE&GOTO:EOF
TOP
2008-03-07

Exit - Exit on key pressed with customized message

Description:
Letting the PAUSE command show the "Press any key to continue" message on exit may cause some confusion, since the application will finish and not continue. An ECHO command preceding the PAUSE command can be used to show a customize message. The text output of the PAUSE command can be omitted by piping its output into the NUL device.
Script:
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 ::: -- End of application --
ECHO.&ECHO.Press any key to end the application.&PAUSE>NUL&GOTO:EOF
TOP
2008-03-07

Exit Delayed - Delayed exit without user interaction

Description:
As you develop DOS batch files you may find it annoying to have to hit a key when the application finished just to close the window. You may want to have it close automatically but still being able to briefly scan over the execution result shown in the window.
A way to create a delay in a DOS batch program is to ping the localhost or 127.0.0.1. Sending 2 pings (ping –n 2 ...) will cause a delay of very close to one second. Invoking multiple pings as needed gives control about the delay time. Showing the remaining delay time in the window TITLE will even let the user know what`s going on.
I.e. replace the pause statement added earlier with the following code lines and run the application again. The menu will show a countdown of 5 seconds before closing the application. Changing the number 5 to 10 would result in a 10 second countdown.

What it`s good for:
  • Closing an application without user interaction
  • Leave enough time to view execution results
  • User can hit Pause on the keyboard to keep the window open
Script:
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 ::: -- End of application --
FOR /l %%a in (5,-1,1) do (TITLE %title% -- closing in %%as&ping -n 2 -w 1 127.0.0.1>NUL)
TITLE Press any key to close the application&ECHO.&GOTO:EOF
TOP
2008-03-07

Echo Empty Line - How to use ECHO to output an empty line

Description:
To ouptut an empty line using the ECHO command simply append a dot to the command. Otherwise the ECHO command will show the current echo state. In fact it appears to be save to always use the dot.
Script:
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 echo
echo This line is followed by an empty line.
echo.
echo.Simply always use the dot when echoing text
Script Output:
 DOS Script Ouput 
ECHO is on.
This line is followed by an empty line.

Simply always use the dot when echoing text
TOP
2008-03-07

Multiple Commands in Single Line - How to enter multiple commands into a single line

Description:
Use & to separate multiple commands within a single command line.
Script:
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 cls&dir
for /l %%a IN (10,-1,0) do @echo.%%a:&echo.This is line number %%a
TOP
2008-03-07

Multiple Lines for Single Command - How to continue a command in the next line

Description:
Use ^ as the very last character in a line if you with to continue the command in the next line.
Script:
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 echo.1. This all goes ^
in line one
echo.2. This all goes ^
in line two
Script Output:
 DOS Script Ouput 
1. This all goes in line one
2. This all goes in line two
TOP
2008-03-07

Escape Characters - Escaping special characters in DOS batch when delayed variable expansion is enabled or disabled

Description:
The command processor handles some characters in a special way and these characters won`t show up in the output as expected when using i.e. the ECHO command. The exclamation mark is handled differently if Delayed Expansion is enabled or disabled.
Script:
Download: BatchEscape.bat  
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 @ECHO OFF
SETLOCAL ENABLEEXTENSIONS

SETLOCAL DISABLEDELAYEDEXPANSION
echo.delayed expansion is DISABLED
echo.1. ^^! :exclamation mark
echo.2. !! :exclamation mark
echo.3. ! :exclamation mark
echo.4. %% :percent
echo.5. ^& :ampersand
echo.6. ^| :vertical line
echo.7. ^^ :caret
echo.

SETLOCAL ENABLEDELAYEDEXPANSION
echo.delayed expansion is ENABLED
echo.1. ^^! :exclamation mark
echo.2. !! :exclamation mark
echo.3. ! :exclamation mark
echo.4. %% :percent
echo.5. ^& :ampersand
echo.6. ^| :vertical line
echo.7. ^^ :caret
echo.
Script Output:
 DOS Script Ouput 
delayed expansion is DISABLED
1. ^! :exclamation mark
2. !! :exclamation mark
3. ! :exclamation mark
4. % :percent
5. & :ampersand
6. | :vertical line
7. ^ :caret

delayed expansion is ENABLED
1. ! :exclamation mark
2. exclamation mark
3. exclamation mark
4. % :percent
5. & :ampersand
6. | :vertical line
7. ^ :caret
TOP
2008-03-07

Command Grouping - Grouping Commands in blocks using Parentesis

Description:
Use parenthesis to group commands into a block. Command blocks are useful in combination with e.g. IF or FOR commands.
An opening parenteses in a line will tell command processor that more lines will follow.
Script:
Download: BatchCommandBlock.bat  
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 @ECHO OFF

for /l %%a IN (4,-1,0) do (
    echo.%%a: First  command in block
    echo.   Second command in block
)
echo.
if exist "c:\windows" (
    echo.The c:\windows directory exist.
    set "IsWin=YES"
) ELSE (
    echo.The c:\windows directory doesn’t exist.
    set "IsWin=NO"
)
echo.Is this a windows pc?  %IsWin%
Script Output:
 DOS Script Ouput 
4: First  command in block
   Second command in block
3: First  command in block
   Second command in block
2: First  command in block
   Second command in block
1: First  command in block
   Second command in block
0: First  command in block
   Second command in block

The c:\windows directory exist.
Is this a windows pc?  YES
TOP
2008-03-07

Conditional Execution - Conditional Execution Based on Result of Previous Command

Description:
Command1 && SuccessCommand
Command1 || FailCommand
Command1 && SuccessCommand || FailCommand

The && operator can be used to execute a command only when the previews command succeeded.
The || operator can be used to execute a command only when the previews command failed.

Example 1
Show a message only when the string "ERROR" exist in the logfile.log file. The find command succeeds when the string "ERROR" exist in logfile.log. The output of the find command is redirected into the NUL devise since we don`t want to see any of its output in the output window.

Example 2
Show a message only when the string "ERROR" doesn`t exist in the logfile.log file. The find command fails when the string "ERROR" doesn`t exist in logfile.log. The output of the find command is redirected into the NUL devise since we don`t want to see any of its output in the output window.

Example 3
The Conditional Execution operators are useful with many DOS commands, i.e. the SET command.

Note
Be careful when combining the operators, i.e.:
Command1 && (CommandBlock2) || (CommandBlock3)
  • If Command1 fails then CommandBlock2 will be skipped and CommandBlock3 will be executed.
  • If Command1 succeeds then CommandBlock2 will be executed.
  • If Command2 fails then CommandBlock3 will also be executed!!

To avoid this pitfall force CommandBlock2 to succeed, i.e. using a simple REM as last block command:
Command1 && (CommandBlock2 & REM) || (CommandBlock3)

or: 
Command1 && (
    CommandBlock2
    REM force success
) || (
    CommandBlock3
)
Script:
Download: BatchConditionalExecution.bat  
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 @ECHO OFF

echo.
echo.1:
echo.   ...finding 'ERROR' in logfile.log
find "ERROR" logfile.log>NUL && (
    echo.   yes, "ERROR" in logfile
)

echo.
echo.2:
echo.   ...finding 'ERROR' in logfile.log
find "ERROR" logfile.log>NUL || (
    echo.   no "ERROR" in logfile
)

echo.
echo.3:
set "v=old_value"
set /p "v=   ...enter a value or just hit ENTER: " && (
    echo.   The user entered a value, the variable v changed.
) || (
    echo.   The user just hit Enter, the variable v remains unchanged.
)
echo.   v is now: %v%
Script Output:
 DOS Script Ouput 
1:
   ...finding 'ERROR' in logfile.log

2:
   ...finding 'ERROR' in logfile.log
   no "ERROR" in logfile

3:
   ...enter a value or just hit ENTER: 
   The user just hit Enter, the variable v remains unchanged.
   v is now: old_value
TOP
2008-03-14

Open the Registry Editor at a given Key - Opening the Registry Editor at a defined Key

Description:
It`s known that opening the registry editor regedit.exe it will have the last registry key remembered and opens right where the it left off the last time it was running. The last registry key is being remembered in the registry itself using the LastKey value in HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Regedit. To have regedit.exe open up at a specific location we just have to set the LastKey value properly before invoking regedit.exe. This can be done with the REG command.
Script:
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 rem open regedit.exe at HKEY_CURRENT_USER\Software\Microsoft
set "showkey=HKEY_CURRENT_USER\Software\Microsoft"
REG ADD "HKCU\Software\Microsoft\Windows\CurrentVersion\Applets\Regedit" /v "LastKey" /d "%showkey%" /f
start /b regedit
TOP
2008-03-19

RunAs Administrator - Force a batch to run as different user via RunAs command

Description:
Force a batch to run as different user via RunAs command. This snippet checks the USERNAME environment variable. If it`s not `Administrator` then it automatically restart the batch with Administrator credentials using the RunAs command. Administrator password is required.
Script:
Download: DosRunAsAdmin.bat  
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 @echo off
echo.Current User is '%USERNAME%'

rem -- Let's make sure this batch runs as Administrator --
set "RunAsUser=Administrator"
if "%USERNAME%" NEQ "%RunAsUser%" (
    RUNAS /user:%RunAsUser% "cmd /c %~f0"||PAUSE
    GOTO:EOF
)

rem -- your code goes below here --
echo.Hello World

ECHO.&PAUSE&GOTO:EOF
Script Output:
 DOS Script Ouput 
Current User is 'DosItHelp'
Enter the password for Administrator:
Attempting to start cmd /c C:\dostips\DosRunAsAdmin.bat as user "DOSTIPS_PC\Administrator" ...


---- RunAs now opens a new window ----

Current User is 'Administrator'
Hello World

Press any key to continue . . .
TOP
2008-03-28

Does String1 begin with String2? - Check if one string starts with another

Description:
Knowing a certain character combination that never occurs in string1 can help solving the exercise. Lets say @@@ never occurs in string1 then we can use it as prefix for string1 and reformulate the question to: Does string1 alter if we delete any occurrence of @@@+string2 within string1. If string1 alters then if string1 start string2 then string 1 will alter otherwise not.
Script:
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 SETLOCAL ENABLEDELAYEDEXPANSION
set s=@@@%string1%
if "%s%"=="!s:@@@%string2%!=" (
    echo.string1 doesn`t begin with string2
) ELSE (
    echo.string1 begins with string2
)
TOP
2008-03-21

Date Time for Unique String - Create a unique string using current date and time

Description:
A string unique to the local host can be created out of the %date% and %time% system environment variables.
For convenience the unique string created here will be a number in the format YYYYMMDDHHMMSSff whereas ff are the 1/100th fractions of a second. As long nobody modifies the system time and the command is not being called twice within a 1/100th of a second, each created UNIQUE string will be unique and in a sorting order.
The example described here assumes that the %date% variable uses the format day MM/DD/YYYY and the %time% variable uses the format HH:MM:SS.ff.
As the %time% variable may return only one digit for the hour before 10.00 AM and put a spacer to fill the missing 10th digit we will substitute the space characters in %time% with 0 by using %time: =0%.
Script:
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 for /f "tokens=2-8 delims=/:. " %%A in ("%date%:%time: =0%") do set "UNIQUE=%%C%%A%%B%%D%%E%%F%%G"
echo.%UNIQUE%
echo.%date% %time%
echo.%date% %time: =0%
Script Output:
 DOS Script Ouput 
2006010501060696
Thu 01/05/2006  1:06:06.96
Thu 01/05/2006 01:06:06.96
TOP
2008-03-21

File Line Count - Use FIND command to count file lines, store line count into a variable

Description:
Running the FIND command with option /v and empty search string will find all lines
Running the FIND command with option /c will output the line count only.
The FOR command with option /f will parse the output, the line count in this case, and the set command put the line number into the cnt variable.
Script:
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 set file=textfile.txt
set /a cnt=0
for /f %%a in ('type "%file%"|find "" /v /c') do set /a cnt=%%a
echo %~1 has %cnt% lines
Script Output:
 DOS Script Ouput 
textfile.txt has 50 lines
TOP
2008-03-21

File Size in Bytes - Use FOR command to determine the file size in bytes

Description:
Use the `z` specifier of FOR variable references to get the size of a file.
Script:
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 set "filename=myfile.txt"
for %%A in (%filename%) do echo.Size of "%%A" is %%~zA bytes
Script Output:
 DOS Script Ouput 
Size of "myfile.txt" is 57006 bytes
TOP
2008-03-21

Check File for Zero Bytes - Use FOR command to show or delete empty files

Description:
Use the `z` specifier of FOR variable references to get the size of a file. Then show or delete the file if the size is zero.
Script:
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 set "filemask=myfile*.txt"
for %%A in (%filemask%) do if %%~zA==0 echo."%%A" is empty
Script Output:
 DOS Script Ouput 
"myfile2.txt" is empty
"myfile7.txt" is empty
"myfile8.txt" is empty
TOP
2008-03-21

Unicode to Ansi - Convert a file to Ansi

Description:
An easy way to convert an UNICODE encoded file to ANSI is by running a TYPE command in a new instance of CMD.exe with /A option and piping the output into a new file.
The following script converts a text file named myfile.txt into the ANSI encoded file named myansifile.txt.
Note myfile.txt can be UNICODE or ANSI the result will always be an ANSI encoded file.
Script:
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 cmd /a /c type myfile.txt>myansifile.txt
TOP
2008-03-21

Ansi to Unicode - Use FOR command to show or delete empty files

Description:
An easy way to convert an ANSI encoded file to UNICODE is by running a TYPE command in a new instance of CMD.exe with option /U and piping the output into a new file.
The following command converts a text file named myfile.txt into the UNICODE encoded file named myunicodefile.txt.
Note that myfile.txt should be ANSI for this to work correctly.
Script:
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 cmd /u /c type myfile.txt>myunicodefile.txt
TOP
2008-03-21

Drive Types - List all drives connected and corresponding types, i.e. Fixed, CD-ROM, Removable

Description:
The FSUTIL program can be used from the command line to query information about the connected drives.

Return all currently connected drives:
fsutil fsinfo drives
Returns e.g.: Drives: C:\ D:\ E:\ F:\

Return the drive type for a given drive:
fsutil fsinfo drivetype D:\
Returns e.g.: D:\ - Fixed Drive

To get the drive type of all drives parse the output of fsutil fsinfo drives with a FOR command and run fsutil fsinfo drivetype for each drive. However some experimenting showed that funny things happen when parsing the result of fsutil fsinfo drives using the FOR command, some line feeds seem to be missing. Piping the fsutil output through the find command seems to resolve this problem.
Script:
Download: BatchDriveType.bat  
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 @ECHO OFF
set "drlist="
for /f "tokens=*" %%A in ('fsutil fsinfo drives^|find /V ""') do (
    set "dr=%%A"
    call set "drlist=%%drlist%% %%dr:~-3%%"
)
for %%A in (%drlist%) do fsutil fsinfo drivetype %%A
Script Output:
 DOS Script Ouput 
C:\ - Fixed Drive
D:\ - Fixed Drive
E:\ - CD-ROM Drive
F:\ - Removable Drive
TOP
2008-04-01

SET /A - Basic Integer Arithmetic

Description:
The SET /A command can be used for basic arithmetic.
You can write SET /a y=3*x or SET /a y=3*%x%. Both are correct. The command interpreter is smart enough to recognize variables within a formula.
Script:
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 set /a x=20
set /a y=3*x
set /a y+=140
set /a y/=2
echo.y = %y%
Script Output:
 DOS Script Ouput 
y = 100
TOP
2008-04-01

Floating Point Arithmetic - Working around the limitations if the command processor

Description:
Floating point arithmetic can be achieved by moving the fractions into the integer. I.e. A floating point equitation using values with 3 digits after the dot can be calculated as follows: 
Floating Point: 12.055 + 1.001 = 13.056
Integer:        12055 + 1001 = 13056
Script:
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 set /a y=12055 + 1001
echo.y = %y%
Script Output:
 DOS Script Ouput 
y = 13056
TOP
2008-04-01

Percent - Basic Percent arithmetic

TOP
2008-04-01

Large Integers - Working around the limitations if the command processor