Zero byte file
Encyclopedia
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 file
s; 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
Computer file
A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...
containing no data
Data
The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...
; 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
Word processor
A word processor is a computer application used for the production of any sort of printable material....
document
Document
The term document has multiple meanings in ordinary language and in scholarship. WordNet 3.1. lists four meanings :* document, written document, papers...
, an image file with zero by zero dimensions, or an audio file of length zero seconds usually still contains metadata
Metadata
The term metadata is an ambiguous term which is used for two fundamentally different concepts . Although the expression "data about data" is often used, it does not apply to both in the same way. Structural metadata, the design and specification of data structures, cannot be about data, because at...
identifying the file format
File format
A file format is a particular way that information is encoded for storage in a computer file.Since a disk drive, or indeed any computer storage, can store only bits, the computer must have some way of converting information to 0s and 1s and vice-versa. There are different kinds of formats for...
and describing some basic attributes of the file. Some very simple file formats do not use metadata, such as ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
text file
Text file
A text file is a kind of computer file that is structured as a sequence of lines of electronic text. A text file exists within a computer file system...
s; 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
Cache
In computer engineering, a cache is a component that transparently stores data so that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere...
in memory
Random-access memory
Random access memory is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order with a worst case performance of constant time. Strictly speaking, modern types of DRAM are therefore not random access, as data is read in...
and only flushed to disk at a later time (page cache
Page cache
In computing, page cache, sometimes ambiguously called disk cache, is a "transparent" buffer of disk-backed pages kept in main memory by the operating system for quicker access. Page cache is typically implemented in kernels with the paging memory management, and is completely transparent to...
), 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
Filename
The filename is metadata about a file; a string used to uniquely identify a file stored on the file system. Different file systems impose different restrictions on length and allowed characters on filenames.A filename includes one or more of these components:...
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
Revision control
Revision control, also known as version control and source control , is the management of changes to documents, programs, and other information stored as computer files. It is most commonly used in software development, where a team of people may change the same files...
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