Batch script variable not working right

Question

Well... I try to dabble in batch as little as possible, and I'm mainly a C/C#/C++ man. My problem is that my script does two nested FOR loops where I run through the 'Users' folder first and snag the user names and then through other folders:

 set BaseDir=%CD%
 cd C:\Users
 for /F %%I in ('DIR *.* /B /O:-D') do (
     set UserName=%%I
     echo %UserName%
 )
 cd %BaseDir%

This roughly demonstrates the problem. Maybe it's my C++ style formatting? Maybe I'm dumb when it comes to batch? Assuming I have 3 users on my system (Admin, User1, User2; in that order) this will print:

 Admin
 Admin
 Admin

Totes wrong. If one were to call echo on %%I everything would go according to plan:

 Admin
 User1
 User2

Am I missing something here as far as variables go, or what's the deal? DOS doesn't like variable re-assignment? Thnx in advance. (specs: Windows 7, notepad, cmd as admin)

You might be having a conflict with the predefined username variable. What happens if you change that variable from UserName to UserName2 (or similar) — billinkc
– billinkc, Commented Sep 8, 2011 at 19:48
Wut? I actually just solved my problem facepalm. The solution is "elusive". One has to set Delayed Expansion... basically, it's like we're back in 1969... — user850275
– user850275, Commented Sep 8, 2011 at 19:53
I believe me saying the answer in my head telepathically went to you while I was typing my answer 0.o — Anthony Miller
– Anthony Miller, Commented Sep 8, 2011 at 19:55
Also note that you should use cd /D or pushd instead of just cd. The code as written won't work if C isn't the current drive. — Harry Johnston
– Harry Johnston, Commented Sep 8, 2011 at 22:32

Anthony Miller · Accepted Answer · 2011-09-08 19:54:51Z

2

Since you are changing a variable within the FOR loop, you need to enable delayed expansions:

SETLOCAL ENABLEDELAYEDEXPANSION
cd C:\Users
for /F %%I in ('DIR *.* /B /O:-D') do (
 set UserName=%%I
 echo %UserName%
)

EDIT A neat way to assign the variables separately to access each instance outside of the loop

SETLOCAL ENABLEDELAYEDEXPANSION
SET count=1
    cd C:\Users
    for /F %%I in ('DIR *.* /B /O:-D') do (
     set UserName!count!=%%I
     echo %UserName!count!%
     set count=!count!+1
    )

answered Sep 8, 2011 at 19:54

Anthony Miller

16.1k30 gold badges74 silver badges100 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

user850275 Over a year ago

Indeed, I stumbled on this conclusion almost immediately after I posted... This should be something posted under the documentation. It's bound to be something everyone has to learn once.

Harry Johnston · Accepted Answer · 2011-09-08 22:32:45Z

2

Another option is to use a subroutine:

 pushd C:\Users
 for /F %%I in ('DIR *.* /B /O:-D') do call :perfile %%I
 popd
 goto :eof

 :perfile
 set UserName=%*
 echo %UserName%
 goto :eof

Also note the use of pushd and popd to avoid needing to store the original directory in an environment variable.

answered Sep 8, 2011 at 22:32

Harry Johnston

36.7k7 gold badges74 silver badges169 bronze badges

Collectives™ on Stack Overflow

Batch script variable not working right

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related