Get/open temp file in .NET

Question

I would like to do something like the below. What function returns me an unique file that is opened? so i can ensure it is mine and i wont overwrite anything or write a complex fn generate/loop

BinaryWriter w = GetTempFile(out fn);
w.close();
File.Move(fn, newFn);

Answer 1

There are two methods for this:

• Path.GetTempFileName

  This will create a temporary file and return its name.

• Path.GetRandomFileName

  This will use a cryptographically strong, random string as file name and won't create the file for you.

Usually the first method suffices; the documentation for GetRandomFileName says:

When the security of your file system is paramount, this method should be used instead of GetTempFileName.

Answer 2

Another alternative is the TempFileCollection class. It provides an IDisposable wrapper much like what is suggested in the docs for Path.GetTempFileName().

Answer 3

You can do something like this:

var path = Path.GetTempFileName();
var stream = new FileStream(path, FileMode.Create, FileAccess.Write, FileShare.None);
var writer = new BinaryWriter(stream);
  ...

Answer 4

Can use the GetTempFileName() method to obtain a fairly unique temporary file name.