Question About Batch Variables and the Call Method - windows

Question

I am trying to figure out how to use call appropriately to pass variables backwards (to the original batch file that calls other batch files).
The way I have my batch files currently setup is my main batch file calls other batch files which may then even call a third batch file which creates the variable.
Here are some examples of my scripts so far, for this example I will be focusing on main.bat, VerifyCredentials.bat, and the CreateAdminCreds.bat files. In these I am trying to pass the %AdminUser% and %AdminPass% variables back to main.bat:
main.bat example:
REM Define all the variables that will be updated by other batch files.
set NewCompName= & set DomainUser= & set DomainPass= & set AdminUser= & set AdminPass=
REM Create the variables for the domain tech account and local admin account. Verify tech account can access SCCM file share.
set CredTestVar=0
:CredTestLoop
call CreateCompName.bat & call VerifyCredentials.bat & call TestCredentials.bat
if %CredTestVar% LSS 1 goto CredTestLoop
REM Activate the local admin account and set password
ECHO Enabling Administrator account
net user administrator /active:yes
net user administrator "%AdminPass%"
ECHO.
VerifyCredentials.bat example:
#ECHO off
if not exist Credentials\DomainUser.txt call CreateDomainCreds.bat
if not exist Credentials\DomainPass.txt call CreateDomainCreds.bat
for /f "delims=" %%x in (Credentials\DomainUser.txt) do set DomainUser=%%x
for /f "delims=" %%x in (Credentials\DomainPass.txt) do set DomainPass=%%x
if not exist Credentials\AdminUser.txt call CreateAdminCreds.bat
if not exist Credentials\AdminPass.txt call CreateAdminCreds.bat
for /f "delims=" %%x in (Credentials\AdminUser.txt) do set AdminUser=%%x
for /f "delims=" %%x in (Credentials\AdminPass.txt) do set AdminPass=%%x
CreateAdminCreds.bat example:
#ECHO off
REM Create and define the local administrator credentials
:CreateAdmin
cls
echo.
echo Please enter a new password for the local Administrator account
echo.
set "AdminUser=Administrator"
set /p "AdminPass=Administrator Password:"
goto :ResponseAdmin
:ResponseAdmin
set "AdminAnswer="
cls
echo.
echo The Administrator password is "%AdminPass%"
echo.
set /p "AdminAnswer=Is this correct? (y/n):"
if %AdminAnswer%==y () else (if %AdminAnswer%==n (goto :CreateAdmin) else (goto :ResponseAdmin))
(echo=%AdminUser%) > "Credentials\AdminUser.txt"
(echo=%AdminPass%) > "Credentials\AdminPass.txt"
set "AdminAnswer="
So all of this individually works fine.. but when I get to the step in main.bat where I try to use that variable %AdminPass% for the tech to define the local admin account it doesn't change the password to anything (on restart/lock you can login to local admin without a password)
Can anyone help explain to me why the variable %AdminPass% is not being passed back to main.bat?
I have tested this passing theory like this:
test1.bat
#ECHO off
set testvar=
echo testvar is currently equal to %testvar%
REM this returns "testvar is currently equal to"
call test2.bat
echo testvar is now equal to %testvar%
REM this returns "testvar is now equal to something"
test2.bat
#ECHO off
set testvar="something"
and this successfully changes testvar to something for the second echo in the test1.bat file.
Thank you in advance for any help.

Answer 1

When a cmd instance starts, it is provided with a set of string variables which form the environment (always strings - if the value of any string is all-numeric, then it can often be used in calculations.)
Any batch file that runs within that instance can modify, add to, or delete variables. Hence running batch files A and B in that order would allow B to see values established by A, but in the reverse order, those values would not be set.
It's therefore usual practice to follow the initial #echo off command (which turns command-regurgitation to the console for debugging OFF) by a setlocal command, which itself has various options. Fundamentally, a setlocal establishes a local environment with a copy of the environment as it stood when the setlocal was executed.
setlocals may be nested, and are closed by an endlocal command or by reaching the physical end-of-file, whereupon the environment is restored to its condition at the time the matching setlocal was executed. Note that this applies only to the environment, it does not affect the setting of the durrent directory or drive for instance.
So, if A calls B then B will NOT manipulate A's environment if B uses setlocal. If B has no setlocal then it will manipulate A's environment BUT if run from the prompt, it will manipulate the cmd instance's environment, which is generally undesirable.
There is a method to transmit the variable "over the endlocal barrier" like this:
endlocal&set "fred=%fred%"
which seems quite bizarre. What this does is use cmd's parser. The entire line is parsed, and %fred% is replaced by the current value of the variable fred within the inner environment, and then the line endlocal&set "fred=fredsvalue" is executed; two commands, serially. So the inner environment is discarded and then the variable in the calling environment is set to the value.
So - you pays your money, you takes your choice. Use setlocal in the called routines, and you'll need to jump the endlocal barriers. Omit the setlocal and the called routine will manipulate the current environment.