?
Solved

NUL

Posted on 2011-03-17
4
Medium Priority
?
713 Views
Last Modified: 2012-05-11
Hi, can you please explain to me what is "NUL"? Google it but no luck.
set p=%1

if not exist %p%\nul mkdir %p%

Open in new window

Thanks
0
Comment
Question by:zhshqzyc
  • 2
4 Comments
 
LVL 3

Expert Comment

by:OrenRozen
ID: 35156342
0
 
LVL 43

Accepted Solution

by:
Steve Knight earned 200 total points
ID: 35156348
Well NUL is a device that eats any input sent to it, e.g.

dir > NUL

results in no output unless there are errors,

dir > NUL 2>&1

says to send standard output to NUL and any errors (2>) to same place.

As a file check like this "NUL" exists everywhere so they have used it to check if a directory exists.  

if exist %p% mkdir %p%

then it would also check if a file of the same name existed for instance.

You could just do:

mkdir  "%~1" >NUL 2>&1

The ~ removes the quotes if existing so they can be re-added to make sure they are there for a path with spaces in.

Steve
0
 
LVL 43

Expert Comment

by:Steve Knight
ID: 35156354
Didn't notice only 50 points :-(
0
 
LVL 13

Expert Comment

by:Rick
ID: 35156356
0

Featured Post

Get your problem seen by more experts

Be seen. Boost your question’s priority for more expert views and faster solutions

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

The following is a collection of cases for strange behaviour when using advanced techniques in DOS batch files. You should have some basic experience in batch "programming", as I'm assuming some knowledge and not further explain the basics. For some…
Using dates in 'DOS' batch files has always been tricky as it has no built in ways of extracting date information.  There are many tricks using string manipulation to pull out parts of the %date% variable or output of the date /t command but these r…
The video will let you know the exact process to import OST/PST files to the cloud based Office 365 mailboxes. Using Kernel Import PST to Office 365 tool, one can quickly import numerous OST/PST files to Office 365. Besides this, the tool also comes…
If you are looking for an automated solution for backup single or multiple Office 365 user mailboxes to Outlook data file, then you can use Kernel Office 365 Backup & Restore tool. Go through the video to check out the steps to backup single or mult…

569 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question