A virtual device in
Unix
Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and ot ...
is a file such as
:/dev/null or
:/dev/urandom, that is treated as a device, as far as user level software is concerned, but is generated by the
kernel
Kernel may refer to:
Computing
* Kernel (operating system), the central component of most operating systems
* Kernel (image processing), a matrix used for image convolution
* Compute kernel, in GPGPU programming
* Kernel method, in machine learnin ...
without reference to hardware.
For instance when
/dev/null is written to, the kernel tells the program it wrote everything to it (without actually writing it anywhere), and when read from, the reading program is told that it has reached the end of the file. It is a device file (it can be made with
mknod
In Unix-like operating systems, a device file or special file is an interface to a device driver that appears in a file system as if it were an ordinary file. There are also special files in DOS, OS/2, and Windows. These special files allow an ...
for instance), but does not reference any hardware.
DOS
DOS is shorthand for the MS-DOS and IBM PC DOS family of operating systems.
DOS may also refer to:
Computing
* Data over signalling (DoS), multiplexing data onto a signalling channel
* Denial-of-service attack (DoS), an attack on a communicat ...
-,
Windows
Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for serv ...
- and
OS/2
OS/2 (Operating System/2) is a series of computer operating systems, initially created by Microsoft and IBM under the leadership of IBM software designer Ed Iacobucci. As a result of a feud between the two companies over how to position OS/2 ...
-like
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
s define the NUL device that performs a similar function (but is implemented as part of the file name processing – no actual file exists by that name).
Unix file system technology
{{Unix-stub
de:Gerätedatei
es:Fichero de dispositivo
pt:Nó de dispositivo
ru:/dev