Batch File Scripting Techniques

In this section you will find a collection of scripting techniques and best practices for batch files.

Most of these techniques apply to either "DOS batch" (also related to as "real DOS" batch or "true DOS" batch), or "NT batch", only in rare cases to both. If you want to use "true DOS" batch techniques in Windows NT 4 or later (2000, XP, Server 2003, Vista) you may have to invoke these batch files with COMMAND /C.
Check the "classification" for a batch technique by hovering your mouse pointer over the ℹ️ information icon at the left of the titles before asking why a batch file doesn't work in your environment.

• Best Practices
• Debugging Batch Files
• Data & Environment Variables
• Devices
• Elevated Privileges
• Files
• Folders
• Internet
• Inventory
• Math
• Miscellaneous
• Network
• Printing
• Processes & Services
• Program Flow
• Registry
• Samples Collections
• Schedulers
• Security
• Time & Date
• UAC
• UNIX Ports
• User Interaction
• Wildcards

Best Practices

1. ℹ️ DOs and DON'Ts When Writing Batch Files
2. ℹ️ Comments
   How to add comments to your batch files.
3. ℹ️ How to prevent code insertion exploits
   
   • ℹ️ Beware of ampersands in file or folder names
     A real-life security vulnerablity, and how to make your batch files safe again.
4. ℹ️ Input validation
   
   • ℹ️ Command line validation
     Test your batch file's input before using it!
   • ℹ️ Parameter files
     A safer alternative to command line arguments.
   • ℹ️ Safely using SET /P to prompt for input

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Debugging Batch Files

1. ℹ️ Debug your batch files
   For those rare (?) occasions when your batch files don't do what they were expected to...

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Data & Environment Variables

1. ℹ️ Read and SET environment variables
2. ℹ️ Dynamic environment variables
3. ℹ️ Verify if variables are defined
   With a chapter on "hidden" (dynamic) variables.
4. ℹ️ Validate Variables
   Check if a string matches specific formats.
5. ℹ️ Get string length
   Count the number of characters in a string.
6. ℹ️ Arrays
   Who said the batch language doesn't know arrays? Think again.
7. ℹ️ Delayed variable expansion and FOR loops
   Setting variables inside FOR loops or inside other code blocks.
8. ℹ️ Escape characters
   How to tell CMD.EXE not to interpret certain characters.
9. ℹ️ Doing math in batch files
   You knew you can use the SET command for simple integer math, but how about really big numbers, or floating point?
10. ℹ️ Boolean Logic in Batch Files
    Emulate logical operators in IF statements.
11. ℹ️ Add/remove leading zeroes
    This seemingly simple task often causes batch files to fail, so I listed several techniques here, with their pros and cons.
12. ℹ️ Parameters
    How to parse command line parameters (or arguments).
13. ℹ️ Random Numbers
    Sample batch files to generate random numbers.
14. Strings:
    
    • ℹ️ String Parsing
      Use FOR /F to split and parse strings.
    • ℹ️ String Substitution
      Use the SET command to find and replace a substring in a string.
    • ℹ️ Substrings
      Use the SET command to extract a substring at a fixed position in a string.
    • ℹ️ Convert to Upper or Lower Case
      Use the SET command to convert a string to upper or lower case.
    • ℹ️ Align Text to Display as Tables
15. ℹ️ Environment Variables in Windows XP and in Windows 7

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Devices

1. ℹ️ Devices
   Check if a "file" name is a device name.
2. ℹ️ DEVCON
   Manage devices and drivers, a command line utility alternative to the Device Manager.

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Elevated Privileges (UAC)

1. ℹ️ Check and set elevated privileges

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Files

1. ℹ️ Rename files
   The use of wildcards in the REN command
2. Read files
   
   • ℹ️ FOR /F overview
     Read lines from a file or from another command's output.
   • ℹ️ FOR /F's tokens and delims
     Explanation of "tokens=... delims=..." with hands-on examples.
3. Write files
   
   • ℹ️ Redirection overview
     Send screen output to a file or to the next command.
   • ℹ️ Redirection and streams explained
     Standard error, standard output and console "streams" explained.
   • ℹ️ The TEE command
     Redirect output to a file and simultaneously display it on screen (requires "third party" software and/or scripts).
4. ℹ️ Read File Properties
   Read a file's attributes, size, extension, last-modified date, parent folder, and more.
5. ℹ️ Read File and Product Versions
   Read a file's file version, product version, and more.
6. File Encoding
   
   • ℹ️ Detect file encoding
     Detect whether a file is encoded in ASCII or Unicode
   • ℹ️ ASCII vs. Unicode
     Convert ASCII to Unicode vv.
   • ℹ️ Base64
     Encode and decode files to and from base64.
   • ℹ️ Hexadecimal
     Encode and decode files to and from hexadecimal.
   • ℹ️ File hashes
     Generate a cryptographic hash (e.g. MD5) for a file.
7. ℹ️ Open Files
   Use the START command to open a file with its associated program.
8. ℹ️ Read INI Files
   Sample batch file to read INI files.
9. ℹ️ Temporary Files
   Some notes on temporary files as used by my batch samples.
10. ℹ️ Useful PDF Commands
    A collection of command lines to merge or print PDF files, or count their pages.

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Folders

1. ℹ️ Check if a folder exists
2. ℹ️ Rename folders
   How to use the MOVE command to rename folders
3. ℹ️ FOR /D and FOR /R
   Use the FOR command's /D and /R switches to handle sets of folders instead of files.
4. ℹ️ RD
   RD /Q /S works like a DELTREE replacement.

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Internet

1. ℹ️ Get the Default Browser
2. ℹ️ Prompt to download
   Check if utilities are available, and prompt to download if they aren't.
3. ℹ️ E-mail
   Send e-mails from a command line or batch file.
4. ℹ️ FTP
   Automate FTP uploads and downloads.
5. ℹ️ User-Agent strings (Browser IDs)

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Inventory

1. ℹ️ WMIC
   WMI queries from the command line.
   WMI(C) is software/OS oriented, and is known to sometimes return incorrect values for hardware queries (e.g. SATA/IDE/SCSI, serial ports, multiple monitors and screen resolutions).
   Reports can be created by redirection only.
2. ℹ️ MSINFO32.EXE is one of Windows' native inventory tools.
   It is usually located in the folder %ProgramFiles%\Common Files\Microsoft Shared\MSInfo.
   Without command line arguments it will run in GUI mode.
   Type MSINFO32 /? for a list of available command line arguments.
   Reliability is not better than WMI(C)'s, but in some cases MSINFO32's command line may be preferred over WMIC's.
   For reports, use the /REPORT switch.
3. ℹ️ DXDIAG.EXE is Windows' native DirectX diagnostic tool.
   It is usually located in the %windir%\System32 directory.
   Without command line arguments it will run in GUI mode.
   Type DXDiag /? for a list of available command line arguments.
   DXDiag is much more reliable than WMIC and MSINFO32 when it comes to video and sound hardware, but it is also much slower, and it can be used for the local computer only.
   Reports can be saved in plain text (/t switch) or XML (/x switch)
4. ℹ️ DMIDecode is a port of a Linux tool to read, interpret and display DMI (SMBIOS) data.
   It is by far the fastest tool available for detailed information on mainboard, CPU and memory, but it can be used for the local computer only.

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Math

1. ℹ️ Doing math in batch files
   You knew you can use the SET command for simple integer math, but how about really big numbers, or floating point?
2. ℹ️ Format numbers in batch files
   Display numbers in octal or hexadecimal notation, or right aligned.
3. ℹ️ PHP based batch files
   Why not use the powerful features of PHP in batch files?
4. ℹ️ Validate Variables
   Check if a string matches specific formats.

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Miscellaneous

1. ℹ️ Comments
   How to add comments to your batch files.
2. ℹ️ Play with colors in the console
3. ℹ️ AUTOEXEC.BAT
4. ℹ️ Undocumented NT commands
   Hard to find documentation for some commands available in Windows NT and later.
5. ℹ️ PHP based batch files
   Why not use the powerful features of PHP in batch files?
6. ℹ️ UNIX ports
   "Ports" of UNIX commands to Windows NT 4+.
7. ℹ️ Useless tips?
   Strange or unexpected behaviour of some DOS commands, and how to use it to your advantage.
8. ℹ️ (Ab)using the DEBUG command.

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Network

1. ℹ️ Login scripts
   • Connect & disconnect network drives
   • Connect & disconnect network printers
   • Set the default printer
   • Log computer access
   • Log computer status & properties
2. ℹ️ DS Tools
   Directory Services Tools, command line utilities to query and manage Active Directory.
3. ℹ️ E-mail
   Send e-mails from a command line or batch file.
4. ℹ️ RAS
   Manage dial-up connections.
5. ℹ️ Terminal Server
   Command reference for some Terminal Server-only commands.

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Printing

• ℹ️ Print files
  Find the print command for a specific file type, and print the file.
• ℹ️ Use your installed applications' command line switches to print files from the command line.
• ℹ️ Control printers
  Manage printers and print queues on the command line.
• ℹ️ Command line DDE
  Control programs that can act as DDE servers.
• ℹ️ Use GetPrint.vbs to list (non-DDE) Print and PrintTo commands for all registered file types.
• ℹ️ PausePrinting.bat and ResumePrinting.bat
  Pause and resume printing on a specified printer.

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Processes & Services

• ℹ️ Processes
  Manage processes.
• ℹ️ Shutdown
  Shutdown, reboot and logoff commands for "all" DOS, Windows and OS/2 versions, in batch as well as other languages.
• ℹ️ Command line DDE
  Control programs that can act as DDE servers.
• ℹ️ SC
  Manage services with SC.EXE.

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Program Flow

• ℹ️ Conditional execution
• ℹ️ FOR loops
  FOR loops in general.
• ℹ️ FOR loops interactive demo
  Try for yourself how different OS versions handle FOR loops' "lists" differently.
• ℹ️ NT FOR loops
  FOR loops, enhancements in (Windows') CMD.EXE.
• ℹ️ FOR /F
  FOR /F "tokens=... delims=..." explained.
• ℹ️ File attributes in FOR loops
  %%~aI explained, by Carlos M.
• ℹ️ Use punctuation characters to increase the number of variables available in a FOR /F loop
  By Carlos M.
• ℹ️ Use numbers as variables in a FOR loop
  By Leonardo Gutierrez Ramirez.
• ℹ️ Mimic While Loops
  Use GOTO to create the batch equivalents of While and Until loops.
• ℹ️ Continuous loops with FOR /L
• ℹ️ Breaking continuous loops
• ℹ️ Errorlevels
  Use error levels (or actually return codes) to control the flow of a batch file.
• ℹ️ Boolean Logic in Batch Files
  Emulate logical operators in IF statements.
• ℹ️ EXIT
  or how to terminate a batch file.

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Registry

• ℹ️ REGEDIT
  Use REGEDIT non-interactively.
• ℹ️ REG
  Query the registry with REG Query.
• ℹ️ WMIC
  Use WMIC to access the registry, including checking access permissions.
• ℹ️ Search the registry
  Use REG Query /F to search the registry.

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Samples Collections

• ℹ️ Browse the MS-DOS examples
  An old collection of batch file scripting techniques, most of them for MS-DOS only.
• ℹ️ Clever Tips and Tricks
  Several tips sent to me by visitors of this site.
• ℹ️ Batch HowTos
  An new collection of batch file scripting techniques, most of them for Windows NT 4 and later only.
• ℹ️ How To ...
  A really old collection of batch file scripting techniques, most of them for MS-DOS only.
  The page will be opened in a new window because the frameset is incompatible with the DHTML menu and the stylesheet switcher.
• ℹ️ Poor man's admin tools
  A collection of scripts that can be used to replace resource kit utilities or commands no longer available in recent Windows versions.
• ℹ️ Scripts for Windows Administrators
  Batch files, KiXtart, Perl, Rexx and VBScript.
• ℹ️ Solutions found on alt.msdos.batch
  Several clever scripting solutions from the alt.msdos.batch and alt.msdos.batch.nt newsgroups.
  Most of these are from the previous millennium, but still hold their own.
• ℹ️ Third Party Batch Files
  Complete scripts sent to me by visitors of this site.
• ℹ️ Useful NT commands for Windows Administrators
  Powerful "one-liners" for the command prompt.
• ℹ️ Useless tips?
  Strange and unexpected behaviour, for which I can't always find any good use.
• ℹ️ UNIX Ports
  Some scripts to compensate for the missing (UNIX) commands in DOS & Windows.
• ℹ️ PHP based batch files
  Not true batch files, as they require PHP, but if you do happen to have PHP installed on your PC...

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Schedulers

• ℹ️ The AT command
• ℹ️ How to build JT command lines
• ℹ️ Help for the JT command
• ℹ️ The SCHTASKS command

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Security

• ℹ️ Security Configuration with SeCEdit and MMC
  Set permissions, inheritance and ownership on files, folders and registry keys.
• ℹ️ Manage permissions with SubInAcl
• ℹ️ Check registry access permissions with WMIC

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Time & Date

• ℹ️ DATE and TIME in MS-DOS
  The basic syntax and some strange ways of using the DATE and TIME commands in COMMAND.COM.
• ℹ️ DATE and TIME in NT: the basics
  The basic syntax and some simple examples of date math in CMD.EXE.
• ℹ️ Parsing DATE and TIME in NT
  How to extract the day, month, year, hours, minutes; andvanced syntax and some not-so-basic examples of date math in CMD.EXE.
• ℹ️ Advanced Date Math in NT
  Add days or weeks to the current day, subtract days or weeks, find the timespan between two dates, find the weekday of any date.
• ℹ️ Batch examples using DATE and TIME
  From very basic to really advanced: samples of date and time manipulation in CMD.EXE.
• ℹ️ Read the CMOS Real Time Clock
  Advanced technique using DEBUG.EXE to read date and time from the Real Time Clock.
• ℹ️ Schedulers
  Use batch files or the command line to manage scheduled tasks.
• ℹ️ Delays
  Several techniques to make batch files wait for a while.

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UNIX Ports

• ℹ️ UNIX Ports
  Some scripts to compensate for the missing (UNIX) commands in DOS & Windows.

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User Interaction

• ℹ️ User Input
  How to make your batch files prompt for user input.
• User Output
  
  • ℹ️ Error Messages
    Display error messages in the local system language.
  • ℹ️ Popup Messages
    Generate popup messages with your batch files.
  • ℹ️ ANSI colors
    Use ANSI sequences to color text and backgrounds
• ℹ️ Neat Dialog Boxes in Batch Files
  My collection of batch tools to display real dialog boxes.
• ℹ️ Hide or minimize the console window

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Wildcards

• ℹ️ Wildcards Mess
  A short explanation of DOS wildcards, and how they may get you into trouble.

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