C# Signature:

[DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
[return: System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.I1)]
static extern bool CreateSymbolicLink(string lpSymlinkFileName, string lpTargetFileName, SYMBOLIC_LINK_FLAG dwFlags);

VB.NET Signature:

<DllImport("kernel32.dll", SetLastError:=True, CharSet:=CharSet.Auto)> _
Private Shared Function CreateSymbolicLink(ByVal lpSymlinkFileName As String, ByVal lpTargetFileName As String, ByVal dwFlags As SYMBOLIC_LINK_FLAG) As Boolean
End Function

User-Defined Types:

SYMBOLIC_LINK_FLAG

A DWORD or in .NET a UInt32.

0x0 The link target is a file.

0x1 The link target is a directory.

Return Codes

Use Win32Exception & SetLastError = true to get error details, when return code is false.

new System.ComponentModel.Win32Exception()  // gets last WinAPI error, e.g., File Exists

Without administrator access, CreateSymbolicLink returns true, without creating a new link.

If lpSymlinkFileName already exists, CreateSymbolicLink returns false.

If lpTargetFileName does not exist, CreateSymbolicLink returns true. Since the lpTargetFileName may or may not exist, when lpSymlinkFileName is next used, this makes sense.

Alternative Managed API:

Do you know one? Please contribute it!

Notes:

The unmanaged prototype contains a return directive because the CreateSymbolicLink API function returns BOOLEAN, a one-byte data type. The default marshaling for bool is four bytes (to allow seamless integration with BOOL return values). If you were to use the default marshaling for BOOLEAN values, it's likely that you will get erroneous results. The return directive forces PInvoke to marshal just one byte of the return value. Source: http://www.informit.com/guides/content.aspx?g=dotnet&seqNum=762&ns=16196

Tips & Tricks:

The MSDN documentation describes that the created link may be an absolute or relative path.

A relative path may be created:

• If the lpSymlinkFileName and lpTargetFileName are on the same drive
• And the lpTargetFileName is a relative path starting with ".\".

Otherwise the link will be created with an absolute path to lpTargetFileName.

To refresh an existing symbolic link: delete the link (File.Delete) and re-create it.

Also, The parent directory of lpSymlinkFileName must already exist. This is similar to other API's for creating files, which require the parent to exist.

Sample Code:

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