Equivalent to Unix /dev/null for Windows (need black hole for output)

Posted on 2004-04-10
Last Modified: 2009-07-29
In Unix scripts and C programs, you can redirect output or write to a special file called "/dev/null".  This is useful if you need to write to a file, don't want the output, and don't want to actually create a temporary file and delete it later.

Below is the line of code I wish would work (it does not work):

DoCmd.OutputTo acOutputReport, RptName, acFormatSNP, "/dev/null", False

...where /dev/null is normally a valid file name.

What is the Windows equivalent to Unix's /dev/null?

Question by:geekboysteves
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LVL 17

Expert Comment

ID: 10797721
>> What is the Windows equivalent to Unix's /dev/null?

Possibly XP's "Null Device Driver". On Win9x, there may be a null port you can add for devices/hardware.

Author Comment

ID: 10797749
Thanks but I need more detail.  This is the full content of the link you provided:
Microsoft Windows XP Embedded  
Null Device Driver
The Null Device Driver component provides the functional equivalent of \dev\null in the Unix environment by accepting I/O request packets and returning them to the caller.

There are no services for this component.

Associated Components
No other components interact with this component.

There are no configurable settings for this component.
 Last updated on Friday, August 29, 2003
Not much to go on!
Thanks though.
LVL 17

Expert Comment

ID: 10797891
You'll probably have to install one yourself if one doesn't already exist. I don't have any experience with such so I'm not sure if this will apply to your scenario or not but it seems to be the equivalent to /dev/null on *nix platforms.

"Installing a Null Driver"
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Author Comment

ID: 10797898
I assumed there was something built-in.  I need something I can rely on on any Windows computer.  Isn't there something like PRN: and AUX: from the old DOS days?  Wasn't there a NUL: ?


c:> echo This text will print > PRN:
c:> echo This text is going nowhere > NUL:


LVL 17

Accepted Solution

zzzzzooc earned 125 total points
ID: 10797948
Those should still apply for Win9x/Win2k/WinXP if you can apply them to your scenario.

C:\>echo "Test" > nul

^^ Shouldn't output anywhere. Not sure if " " will work on Win9x though. I just checked with FileMon and there's nothing being written to disk with that.

Author Comment

ID: 10797996


That's it!  I knew it was something like that.  I tried it* on NT4, Windows Server 2003, Windows XP Home and Windows 2000 Server and it works just as /dev/null does under Unix.


* it = echo aaaaaaaaaaaaaaaa > nul

Did not create a file named "nul" and did not display any aaaaaaaaaaaaaaaaaa's or an error.

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