of DR-DOS since 1992, has built-in support for this. An even more complicated situation arises when one needs to copy files between two remote servers. The simple way is to read data from one server, and then to write the data to the second server. See also Core dump Soft copy Hard copy List of file copying software ln (Unix) NTFS junction point Zero copy References Further reading N-level file shadowing and recovery in a shared file system, United States Patent 5043876 Method of file shadowing among peer systems, United States Patent 5276871 Database Shadow Files External links Instructions on how to shadow files for Emacs Computer file systems Copyright law