setlocal, endlocal
When you want to use variables in the command prompt or batch files, you can specify the set command to assign a value to a specific variable name.
However, using the set command as is treats the variable as a global variable.
Because the variable remains after the execution of the batch file, using the same variable name in other batch files or the command prompt may result in unexpected outcomes.
To prevent such issues, you can limit the scope of the variable by using the setlocal and endlocal commands.
How to Use the setlocal and endlocal Commands
Without Using setlocal and endlocal
As an example, create two batch files named caller.cmd and callee.cmd, as follows.
@echo off
set VAR=Hello
call callee.cmd
@echo off
echo %VAR%
When the above caller.cmd is executed, callee.cmd is run, and echo %VAR% is executed within callee.cmd.
Since setlocal and endlocal are not used, the defined variable VAR is treated as a global variable.
Therefore, it can be referenced from callee.cmd, and the string Hello is output.
Using setlocal and endlocal
Next, we’ll modify the previously created caller.cmd and callee.cmd as follows.
@echo off
setlocal
set VAR=Hello
endlocal
call callee.cmd
@echo off
echo %VAR%
Add setlocal and endlocal to caller.cmd, with no changes to callee.cmd.
When you run the above caller.cmd, callee.cmd is executed, and echo %VAR% is executed within callee.cmd.
However, because setlocal and endlocal are used, executing echo %VAR% within callee.cmd does not output anything, as the VAR variable does not exist.
When actually executed, it results in the following:
By using setlocal and endlocal, you can limit the scope of variables.
To prevent unintended variable references, it is recommended to use setlocal and endlocal when creating batch files.