Batch variables

Variable Scope

REM a regular variable
%VAR%

REM if variable is from different scope
!VAR!

Assign Variable

REM assign a variable
set VAR=value
set VAR=value with spaces

REM file contents as variable
set /p VAR < file.txt

REM result of command as variable
echo "hi" > tempfile.txt
set /p VAR < tempfile.txt
DEL tempfile.txt

REM request user input for variable
set /p VAR=

User Input

set /p REPLY=Please Enter Y/N

Math

REM test+=1
set /a test=%test%+1

Delayed Expansion

When the set command is used to set a variable within the scope of a ( and ), it is not parsed until the ( and ) are finished. (So the variable does not contain a value until the scope ends). To get around this, anywhere in your script add:

setlocal enabledelayedexpansion

and then when you want to echo or test your variable within that scope instead of using the syntax

echo %variable%

use the syntax

echo !variable!

Last N chars of Variable

@setlocal enableextensions enabledelayedexpansion
@echo off

set variable=bg layer
echo !variable!
if "x!variable:~-1!"=="xs" (
    echo variable is plural
) else (
	echo variable is not plural
)

pause

Strip Quotes from Variable

echo %~1