Zero byte file

A zero byte file or zero length file is a computer file containing no data; that is, it has a length or size of zero bytes.

Zero byte files cannot be loaded or used by most applications. Even a file describing an empty word processor document, an image file with zero by zero dimensions, or an audio file of length zero seconds usually still contains metadata identifying the file format and describing some basic attributes of the file. Some very simple file formats do not use metadata, such as ASCII text files; these may validly be zero bytes.

Zero byte files may arise in cases where a program creates a file but aborts or is interrupted prematurely while writing to it. Because writes are cached in memory and only flushed to disk at a later time (page cache), a program that does not flush its writes to disk or terminate normally may result in a zero byte file.

In some cases zero byte files may be used to convey information using file metadata (for example, its filename may contain an instruction to a user viewing a directory listing); or to ensure that a directory is nonempty, since some tools such as backup and revision control software treat empty directories differently from nonempty ones.

For example:

the-file-you-were-looking-for-has-been-moved-to-partition-D.txt
if-this-file-is-here-something-broke-in-the-last-run.txt