bat

name	bat
description	Windows Batch (.bat / .cmd) scripting, errorlevel handling, and CMD automation. Use when writing or editing Windows batch files, .bat or .cmd scripts, or CMD automation tasks.

Bat

Script Structure

• Start with @echo off to suppress command echoing
• Use setlocal enabledelayedexpansion for variable manipulation in loops
• End scripts with exit /b %errorlevel% or exit /b 0
• Use REM or :: for comments (prefer REM for compatibility)

Error Handling

• Check %errorlevel% after every command that can fail
• Use if %errorlevel% neq 0 to detect failures
• Use || for simple error handling: command || (echo FAILED & exit /b 1)
• Use && for success chaining: command && echo OK
• Never use exit without /b - it closes the CMD window

Variable Best Practices

• Use set "VAR=value" with quotes to avoid trailing spaces
• Access variables with %VAR% (normal) or !VAR! (delayed expansion)
• Use enabledelayedexpansion for variables that change inside loops
• For arithmetic: set /a "result=%a%+%b%"
• Environment variables: %USERPROFILE%, %TEMP%, %PATH%, %COMPUTERNAME%

File Operations

• Check existence: if exist "file.txt" (echo yes) else (echo no)
• Check nonexistence: if not exist "file.txt" (echo missing)
• Copy: copy /Y "source" "dest"
• Move: move /Y "source" "dest"
• Delete: del /F /Q "file.txt"
• Create directory: if not exist "dir\" mkdir "dir"
• Iterate files: for %%f in (*.txt) do echo %%f
• Recursive: for /r %%f in (*) do echo %%f

String Manipulation

• Substring: %VAR:~0,5% (first 5 chars)
• Replace: %VAR:old=new%
• Trim quotes: %~1 (removes surrounding quotes)
• File path parts: %~dp0 (drive+path), %~n0 (name), %~x0 (extension)
• Length check: if "%VAR%"=="" echo empty

Input/Output

• User input: set /p "NAME=Enter name: "
• Redirect output: >file.txt (overwrite), >>file.txt (append)
• Redirect errors: 2>error.txt
• Combine: >log.txt 2>&1
• Suppress output: >nul 2>&1
• Pipe: command1 | command2
• Find in output: command | findstr "pattern"
• Count lines: find /c /v "" file.txt

Common Patterns

Argument Processing

if "%~1"=="" (echo Usage: %~n0 ^<arg^> & exit /b 1)
if /i "%~1"=="--help" (echo Help text & exit /b 0)

Loop with Counter

set /a count=0
for %%f in (*.txt) do (
    set /a count+=1
    echo !count!: %%f
)

Function (Label)

call :myfunction arg1 arg2
goto :eof

:myfunction
echo Arg1: %~1  Arg2: %~2
exit /b 0

Menu System

:menu
echo 1. Option One
echo 2. Option Two
echo 3. Exit
set /p "choice=Choose: "
if "%choice%"=="1" goto :option1
if "%choice%"=="2" goto :option2
if "%choice%"=="3" exit /b 0
goto :menu

Safety Rules

• Always quote file paths: "C:\Program Files\app.exe"
• Use pushd/popd for directory changes
• Check file existence before delete/copy
• Escape special chars with ^: ^<, ^>, ^|, ^&, ^^
• Test with echo before destructive operations
• Use if exist guards before file operations

Smoke Test Pattern

@echo off
echo === Smoke Test ===
call script.bat arg1 arg2
if %errorlevel% neq 0 (echo FAILED & exit /b 1)
echo PASSED
exit /b 0

Integration with AFTC

• Scripts go in their own template directories under templates/bat/
• Each template has README.md, .bat script, smoke-test.bat
• No cross-platform wrappers needed (.bat is Windows-native)
• The AFTC extension deploys templates when users request batch file tasks