bat脚本for循环适用于CL，但双击时不起作用

Question

I have a batch file and inside the batch file, it looks in a particular directory and saves to a variable, the name of the first directory/file. Here is roughly what I am doing:

FOR /d %%F IN (%INSTALL_DIR%\dir\*) DO (
    set NAME=%%~xnF
    set NAME_DIR=%INSTALL_DIR%\dir\%NAME%
    goto :break
)

When I run this from the command line, it works perfectly and NAME_DIR gets the correct value. However, when I double-click on the file, the NAME variable is blank. NANE_DIR is thus set to %INSTALL_DIR%\\dir. Why does this happen and what can I do to fix it?

For more clarification, from the command line, this is what NAME and NAME_DIR equal when echoed:

NAME:      dir1.3.8
NAME_DIR:  D:\root\path\to\dir\dir1.3.8

This is what is echoed when double clicked:

NAME:      
NAME_DIR:  D:\root\path\to\dir

Answer 1

What RaymondChen told me in the comments worked! I needed to use delayed expansion. The reason for this is that windows executes the for loop as one single instruction and so it fills in all the variables at once before executing the for loop. Since I never had NAME set before the for loop, it would just evaluate to nothing. Therefore NAME_DIR gets an empty string in place of %NAME%. I noticed that when I first ran the script on the command line, it did not work. I ran it again and it worked. I kept running it and it worked every time. Thats because after running the for loop once, the variable is saved and never changed. So the next time I run the code, the variable is not blank anymore, it has the correct value. Now when double clicking, the NAME variable is null at the beginning. After the for loop executes, the value of NAME is updated. Once the script executes and the cmd windows exits, the new value of the variable is lost and it starts all over again. Here is the new code with delayed expansion:

setlocal ENABLEDELAYEDEXPANSION

FOR /d %%F IN (%INSTALL_DIR%\dir\*) DO (
    set NAME=%%~xnF
    set NAME_DIR=%INSTALL_DIR%\dir\!NAME!
    goto :break
)

I added in the setlocal statement and changed %NAME% to !NAME!