There are several different technologies that use the term file shadowing, but the intent of file shadowing within these technologies is to provide an exact copy (or mirror

Mirror (computing)

In computing, a mirror is an exact copy of a data set. On the Internet, a mirror site is an exact copy of another Internet site.Mirror sites are most commonly used to provide multiple sources of the same information, and are of particular value as a way of providing reliable access to large downloads...

 of a set of data).

For file shadowing to be effective, the shadow needs to exist in a separate physical location than the original data. Depending on the reasons behind the shadow operation, this location may be as close as a second harddrive in the same chassis or as far away as the other side of the globe.

External links

• Instructions on how to shadow files for Emacs
  Emacs
  Emacs is a class of text editors, usually characterized by their extensibility. GNU Emacs has over 1,000 commands. It also allows the user to combine these commands into macros to automate work.Development began in the mid-1970s and continues actively...