In some
operating systems, the null device is a
device file that discards all data written to it but reports that the write operation succeeded. This device is called /dev/null
on
Unix and
Unix-like systems, NUL:
(see
TOPS-20) or NUL
on
CP/M and
DOS (internally \DEV\NUL
), nul
on
OS/2 and newer
Windows systems
[1] (internally \Device\Null
on
Windows NT), NIL:
on
Amiga operating systems,
[2] and NL:
on
OpenVMS.
[3] In
Windows Powershell, the equivalent is $null
.
[4] It provides no data to any
process that reads from it, yielding
EOF immediately.
[5] In IBM operating systems
DOS/360 and successors
[a] and also in
OS/360 and successors
[b] such files would be assigned in
JCL to DD DUMMY
.
In programmer jargon, especially Unix jargon, it may also be called the bit bucket [6] or black hole.
/dev/null is described as an empty regular file in Version 4 Unix. [7]
The Version 5 Unix manual describes a /dev/null device with modern semantics. [8]
The null device is typically used for disposing of unwanted output streams of a process, or as a convenient empty file for input streams. This is usually done by redirection.
The /dev/null
device is a
special file, not a
directory, so one cannot move a whole file or directory into it with the Unix
mv
command.
This entity is a common inspiration for technical
jargon expressions and
metaphors by Unix programmers, e.g. "please send complaints to /dev/null
", "my mail got archived in /dev/null
", and "redirect to /dev/null
"—being jocular ways of saying, respectively: "don't bother sending complaints", "my mail was deleted", and "go away". The
iPhone Dev Team commonly uses the phrase "send donations to /dev/null
", meaning they do not accept donations.
[9] The fictitious person name "Dave (or Devin) Null" is sometimes similarly used (e.g., "send complaints to Dave Null").
[10] In 1996,
Dev Null was an animated
virtual reality character created by
Leo Laporte for MSNBC's computer and technology TV series
The Site. Dev/null is also the name of a vampire hacker in the computer game
Vampire: The Masquerade – Redemption. A 2002 advertisement for the Titanium
PowerBook G4 reads The Titanium Powerbook G4 Sends other UNIX boxes to /dev/null.
[11]
The null device is also a favorite subject of technical jokes,
[12] such as warning users that the system's /dev/null
is already 98% full. The 1995
April Fool's issue of the
German magazine
c't reported on an enhanced /dev/null
chip that would
efficiently dispose of the incoming data by converting it to a flicker on an internal glowing
LED.
Dev/Null is also the name of an electronic dance music producer and jungle DJ. [13]
In some
operating systems, the null device is a
device file that discards all data written to it but reports that the write operation succeeded. This device is called /dev/null
on
Unix and
Unix-like systems, NUL:
(see
TOPS-20) or NUL
on
CP/M and
DOS (internally \DEV\NUL
), nul
on
OS/2 and newer
Windows systems
[1] (internally \Device\Null
on
Windows NT), NIL:
on
Amiga operating systems,
[2] and NL:
on
OpenVMS.
[3] In
Windows Powershell, the equivalent is $null
.
[4] It provides no data to any
process that reads from it, yielding
EOF immediately.
[5] In IBM operating systems
DOS/360 and successors
[a] and also in
OS/360 and successors
[b] such files would be assigned in
JCL to DD DUMMY
.
In programmer jargon, especially Unix jargon, it may also be called the bit bucket [6] or black hole.
/dev/null is described as an empty regular file in Version 4 Unix. [7]
The Version 5 Unix manual describes a /dev/null device with modern semantics. [8]
The null device is typically used for disposing of unwanted output streams of a process, or as a convenient empty file for input streams. This is usually done by redirection.
The /dev/null
device is a
special file, not a
directory, so one cannot move a whole file or directory into it with the Unix
mv
command.
This entity is a common inspiration for technical
jargon expressions and
metaphors by Unix programmers, e.g. "please send complaints to /dev/null
", "my mail got archived in /dev/null
", and "redirect to /dev/null
"—being jocular ways of saying, respectively: "don't bother sending complaints", "my mail was deleted", and "go away". The
iPhone Dev Team commonly uses the phrase "send donations to /dev/null
", meaning they do not accept donations.
[9] The fictitious person name "Dave (or Devin) Null" is sometimes similarly used (e.g., "send complaints to Dave Null").
[10] In 1996,
Dev Null was an animated
virtual reality character created by
Leo Laporte for MSNBC's computer and technology TV series
The Site. Dev/null is also the name of a vampire hacker in the computer game
Vampire: The Masquerade – Redemption. A 2002 advertisement for the Titanium
PowerBook G4 reads The Titanium Powerbook G4 Sends other UNIX boxes to /dev/null.
[11]
The null device is also a favorite subject of technical jokes,
[12] such as warning users that the system's /dev/null
is already 98% full. The 1995
April Fool's issue of the
German magazine
c't reported on an enhanced /dev/null
chip that would
efficiently dispose of the incoming data by converting it to a flicker on an internal glowing
LED.
Dev/Null is also the name of an electronic dance music producer and jungle DJ. [13]