Pass login name as a variable in a SQL Server script

I have the following script that I want the production guys to execute using sqlcmd开发者_如何学JAVA. I want to pass the name of the APP_POOL_USER as a variable to the script, since they want it that way. Don't ask me why.

CREATE USER [$(APP_POOL_USER)] FOR LOGIN [$(APP_POOL_USER)] 
  WITH DEFAULT_SCHEMA=[schema]

I get the following error when I execute the code above

Msg 15007, Level 16, State 1, Line 2 '$(APP_POOL_USER)' is not a valid login or you do not have permission.

How can this be done?

EDIT:

This is the batch file to execute it I have so far

@ECHO OFF

SET DB_SERVER_NAME = ".\SQLEXPRESS"
SET APP_POOL_ACCOUNT = "ExUserAccout"




sqlcmd.exe -E -S "%DB_SERVER_NAME%" -i "SQL_DB.sql" -o SQL_DB.log -v APP_POOL_USER="%APP_POOL_ACCOUNT%" 

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The solution was in the batch file.

@ECHO OFF

SET DB_SERVER_NAME=.\SQLEXPRESS
SET APP_POOL_ACCOUNT=ExUserAccout

Don't leave spaces between the equal sign and the variable name and value.