File.ln

You're seeing just the function ln, go back to File module for more information.
Link to this function

ln(existing, new)

View Source (since 1.5.0)

Specs

ln(Path.t(), Path.t()) :: :ok | {:error, posix()}

Creates a hard link new to the file existing.

Returns :ok if successful, {:error, reason} otherwise. If the operating system does not support hard links, returns {:error, :enotsup}.