Environment variable

Environment variables are a set of dynamic named values that can affect the way running processes will behave on a computer.

They are part of the environment in which a process runs. For example, a running process can query the value of the TEMP environment variable to discover a suitable location to store temporary files, or the HOME or USERPROFILE variable to find the directory structure owned by the user running the process.

They were introduced in their modern form in 1979 with Version 7 Unix, so are included in all Unix operating system flavors and variants from that point onward including Linux and OS X. From PC DOS 2.0 in 1982, all succeeding Microsoft operating systems including Microsoft Windows, and OS/2 also have included them as a feature, although with somewhat different syntax, usage and standard variable names.

Details

In all Unix and Unix-like systems, each process has its own separate set of environment variables. By default, when a process is created, it inherits a duplicate environment of its parent process, except for explicit changes made by the parent when it creates the child. At the API level, these changes must be done between running fork and exec. Alternatively, from command shells such as bash, a user can change environment variables for a particular command invocation by indirectly invoking it via env or using the ENVIRONMENT_VARIABLE=VALUE <command> notation. All Unix operating system flavors, DOS, and Windows have environment variables; however, they do not all use the same variable names. A running program can access the values of environment variables for configuration purposes.

Os (Fringe)

"Os" is the 16th episode of the third season of the American science fiction drama television series Fringe, and the 59th episode overall. The episode centered on the Fringe team's investigation into a series of robberies of the element osmium, which they connect to a scientist (Alan Ruck) who is able to defy the laws of physics.

"Os" was written by Josh Singer and Graham Roland, while Brad Anderson served as director. Along with Ruck, the episode also guest starred Jorge Garcia in a brief cameo as a security guard.

On its first broadcast in the United States on March 11, 2011, an estimated 3.76 million viewers tuned in, giving it a 1.5/5 ratings share for those between the ages 18–49. Critical reception to the episode was generally positive, as multiple critics noted that Ruck was well-cast as a scientist just trying to help his son.

Plot

The Fringe team is called to the scene of a robbery of a metal depository; the body of one of the thieves, shot by a security guard, inexplicably floats off the ground, while a second culprit has gotten away. They find that the thief has taken off with a supply of osmium, one of the densest elements, and an autopsy later reveals that the dead thief's body is filled with the metal. Tracking a security card on the body, they enter a warehouse where they find the second culprit, dead, along with the bodies of several more people, all of them paraplegic. Walter (John Noble) notes that the physical properties of osmium (both gravitational and thermal) have been reversed, and by melting the osmium collected from the first victim using liquid nitrogen, they detect the presence of the rarer element lutetium, typically only present in meteorites.

Ansuz (rune)

Ansuz is the conventional name given to the a-rune of the Elder Futhark, ᚨ. The name is based on Common Germanic *ansuz "a god, one of the main deities in Germanic paganism".

The shape of the rune is likely from Neo-Etruscan a (), like Latin A ultimately from Phoenician aleph.

Name

In the Norwegian rune poem, óss is given a meaning of "estuary" while in the Anglo-Saxon one, ōs ᚩ takes the Latin meaning of "mouth". The Younger Futhark rune is transliterated as ą to distinguish it from the new ár rune (ᛅ), which continues the jēran rune after loss of prevocalic *j- in Proto-Norse *jár (Old Saxon jār).

Since the name of a is attested in the Gothic alphabet as ahsa or aza, the common Germanic name of the rune may thus either have been *ansuz "god", or *ahsam "ear (of wheat)".

Development in Anglo-Saxon runes

The Anglo-Saxon futhorc split the Elder Futhark a rune into three independent runes due to the development of the vowel system in Anglo-Frisian. These three runes are ōs ᚩ (transliterated o), æsc ᚫ "ash" (transliterated æ) and ac "oak" ᚪ (transliterated a).