How can I convert a long path to a short path?

There is no direct support in the framework to do this. You have to use the GetShortPathName function using PInvoke.

This is how the signature for this function looks like:

[DllImport(''kernel32.dll'', SetLastError=true, CharSet=CharSet.Auto)]
    public  static extern int  GetShortPathName(string  longPath, [MarshalAs(UnmanagedType.LPTStr)]StringBuilder  ShortPath, [MarshalAs(UnmanagedType.U4)]int  bufferSize);

Download C# Sample GetShortPathName.zip
Download VB.NET sample GetShortPathName_VB.zip