Null device

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 or Unix-like systems, NUL: or NUL on DOS and CP/M, \Device\Null on Windows NT, nul on newer Windows systems, NIL: on Amiga operating systems, and the NL: on OpenVMS. In Windows Powershell, the equivalent is $null. It provides no data to any process that reads from it, yielding EOF immediately. In IBM DOS/360, OS/360 (MFT, MVT), OS/390 and z/OS operating systems, such files would be assigned in JCL to DD DUMMY.

In programmer jargon, especially Unix jargon, it may also be called the bit bucket or black hole.

Usage

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. The rm command is the proper way to delete files in Unix.

Dev Null

Dev Null was an animated virtual reality character created in 1996 by Leo Laporte for MSNBC's computer and technology TV series, The Site. Espresso barista Dev talked with host Soledad O'Brien each weeknight in a five-minute segment. Laporte was awarded a 1997 Northern California Emmy for his nightly performances as cyber character Dev Null.

Background and history

Dev was animated in real time on million-dollar Silicon Graphics Onyx computer. Laporte generated both the voice and actions while wearing a VR motion capture suit. When O'Brien sat at the espresso bar to read email from viewers, Dev flirted with her while answering her computer questions. She recalled, "One of the reasons that segment of the show worked is that I could not see him as I was talking to him, and the segment was unscripted. He was funny, and his jokes were not gags."

While O'Brien looked at a piece of tape on the wall indicating Dev's virtual position, the VR suit captured Laporte's actions, and a computer program translated his body movements to create the character, while other human operators controlled facial expressions and accentuated movements of his hair. The control room juxtaposed O'Brien and Dev on the same set using a switcher.

Null (mathematics)

In mathematics, the word null (from German: null meaning "zero", which is from Latin: nullus meaning "none") means of or related to having zero members in a set or a value of zero. Sometimes the symbol ∅ is used to distinguish "null" from 0. is sometimes called Aleph null.

In a normed vector space the null vector is the zero vector; in a seminormed vector space such as Minkowski space, null vectors are, in general, non-zero. In set theory, the null set is the set with zero elements; and in measure theory, a null set is a set with zero measure.

A null space of a mapping is the part of the domain that is mapped into the null element of the image (the inverse image of the null element).

In statistics, a null hypothesis is a proposition presumed true unless statistical evidence indicates otherwise.

References

Null (Foetus EP)

Null is a Foetus EP released in 1995 by Big Cat in the UK. Null acts as a De facto single for "Verklemmt," released on Gash. Promotional copies of Null were distributed by Sony/Columbia in the US, but the EP had no official US release. Null was later rereleased as half of the Null/Void double-CDEP set.

Track listing

All songs written and composed by J. G. Thirlwell. 

Personnel

References

External links

Null (Intronaut EP)

Null is the first EP by the American post-metal band Intronaut. It was released in 2006 on Goodfellow Records.

Track listing

Credits

References

Dev

Religion

People

First names

Surnames

Device file

In Unix-like operating systems, a device file or special file is an interface for a device driver that appears in a file system as if it were an ordinary file. There are also special files in MS-DOS, OS/2, and Microsoft Windows. They allow software to interact with a device driver using standard input/output system calls, which simplifies many tasks and unifies user-space I/O mechanisms.

Device files often provide simple interfaces to peripheral devices, such as printers and serial ports. But they can also be used to access specific resources on those devices, such as disk partitions. Finally, device files are useful for accessing system resources that have no connection with any actual device such as data sinks and random number generators.

MS-DOS borrowed the concept of special files from Unix, but renamed them devices. Because early versions of MS-DOS did not support a directory hierarchy, devices were distinguished from regular files by making their names reserved words. This means that certain file names were reserved for devices, and should not be used to name new files or directories. The reserved names themselves were chosen to be compatible with "special files" handling of PIP command in CP/M. There were two kinds of devices in MS-DOS: Block Devices (used for disk drives) and Character Devices (generally all other devices, including COM and PRN devices). PIPE, MAILSLOT, and MUP are other standard Windows devices.