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I use Windows 7 x64. You can try this on your computer, too.

Go take any file. Try to rename it to 'aux.svg'. Windows will answer with

The specified device name is invalid.

I tried this on two different computers (also Win7 x64), with the same results.
You can take any file you want. You can not rename it to 'aux.svg'. Dropbox will not download a file with that name. The browser will rename it to '_aux.svg' when downloading. This seems to happen in any directory I cared to try.

What the heck is happening here?

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marked as duplicate by bwDraco, Mokubai, Excellll, LawrenceC, Scott Jul 4 '13 at 3:22

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Most of the Win32 API, including Explorer and the common file dialogs, will not allow you to create files that match a couple old reserved DOS device names such as con, prn, aux. – LawrenceC Jul 3 '13 at 20:32
up vote 13 down vote accepted

This is one of the file names Windows bans for historical reasons. As far as I know, you have no way around it.

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+1 for the link about historical reasons. – bartolo-otrit Mar 13 '15 at 11:37

To add to alexandru's answer:

You can bypass file name parsing by using a path such as:


del and rename in Command Prompt accept such paths. However, it's pointless to rename a file to aux, since you won't be able to access it from other programs.

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As another addition two years later:

You can rename (and modify) to any reserved keyword with cygwin. If it's a directory, you can access it's contents with other programs on Windows, but not itself.

I came across this while compiling a program on a shared folder in a virtual machine. There was a folder named aux in the package, an immovable folder, which I extracted with cygwin formerly. So only way to get rid of is using cygwin again.

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