Dot (Unix)

In a Unix shell, the full stop called the dot command (.) is a command that executes or opens a computer file. The filename is the dot command's first argument. One may specify parameters in a second argument. If no parameters are specified, the sourced file will receive the set of positional parameters available in the current context. If parameters are specified, the sourced file will receive only the specified parameters. In any case, parameter $0 will be the $0 of the current context.

The file does not have to be executable, but must be accessible from a directory defined in the PATH environment variable. The dot command is often used to define environment variables that are accessible within the current process. In contrast to file executed directly as an executable, there won't be a new process opened and the environment definitions defined within apply to the current process or the current shell.

The dot command is not to be confused with a dot file, which is a dot-prefixed hidden file or hidden directory. Nor is it to be confused with the ./scriptfile notation for running commands, which is simply a relative path pointing to the current directory (notated in Unix as a '.' character, and typically outside of the Path variable).

Single UNIX Specification

The Single UNIX Specification (SUS) is the collective name of a family of standards for computer operating systems, compliance with which is required to qualify for to use the "UNIX" trademark. The core specifications of the SUS are developed and maintained by the Austin Group, which is a joint working group of IEEE, ISO JTC 1 SC22 and The Open Group. If an operating system is submitted to The Open Group for certification, and passes conformance tests, then it is termed to be compliant with a UNIX standard such as UNIX 98 or UNIX 03.

Very few BSD and Linux-based operating systems are submitted for compliance with the Single UNIX Specification, although system developers generally aim for compliance with POSIX standards, which form the core of the Single UNIX Specification.

History

1980s: Motivation

The SUS emerged from a mid-1980s project to standardize operating system interfaces for software designed for variants of the Unix operating system. The need for standardization arose because enterprises using computers wanted to be able to develop programs that could be used on the computer systems of different manufacturers without reimplementing the programs. Unix was selected as the basis for a standard system interface partly because it was manufacturer-neutral.

Year 2038 problem

The Year 2038 problem is an issue for computing and data storage situations in which time values are stored or calculated as a signed 32-bit integer, and this number is interpreted as the number of seconds since 00:00:00 UTC on 1 January 1970 ("the epoch"). Such implementations cannot encode times after 03:14:07 UTC on 19 January 2038 (21 years' time), a problem similar to but not entirely analogous to the "Y2K problem" (also known as the "Millennium Bug"), in which 2-digit values representing the number of years since 1900 could not encode the year 2000 or later. Most 32-bit Unix-like systems store and manipulate time in this "Unix time" format, so the year 2038 problem is sometimes referred to as the "Unix Millennium Bug" by association.

Technical cause

The latest time that can be represented in Unix's signed 32-bit integer time format is 03:14:07 UTC on Tuesday, 19 January 2038 (2,147,483,647 seconds after 1 January 1970). Times beyond that will "wrap around" and be stored internally as a negative number, which these systems will interpret as having occurred on 13 December 1901 rather than 19 January 2038. This is caused by integer overflow. The counter "runs out" of usable bits, "increments" the sign bit instead, and reports a maximally negative number (continuing to count up, toward zero). Resulting erroneous calculations on such systems are likely to cause problems for users and other relying parties.

Dot

Dot, DoT or DOT may refer to:

Typography

Slashdot

Slashdot (sometimes abbreviated as /.) is a news website that originally billed itself as "News for Nerds. Stuff that Matters". It features news stories on science and technology that are submitted and evaluated by its users. Each story has a comments section attached to it.

Slashdot was founded in 1997 by Hope College student Rob Malda, also known as "Commander Taco", and classmate Jeff Bates, also known as "Hemos". It was acquired by DHI Group, Inc. (i.e., Dice Holdings International, which created the Dice.com website for tech job seekers.)

Summaries of stories and links to news articles are submitted by Slashdot's own readers, and each story becomes the topic of a threaded discussion among users. Discussion is moderated by a user-based moderation system. Randomly selected moderators are assigned points (typically 5) which they can use to rate a comment. Moderation applies either -1 or +1 to the current rating, based on whether the comment is perceived as either "normal", "offtopic", "insightful", "redundant", "interesting", or "troll" (among others). The site's comment and moderation system is administered by its own open source content management system, Slash, which is available under the GNU General Public License.

Dot (song)

"Dot" is a song by the American punk rock band All, written by singer Scott Reynolds and released as a single and music video from the band's 1992 album Percolater. The single also includes the song "Can't Say", written by bassist Karl Alvarez and drummer Bill Stevenson, and a cover version of "A Boy Named Sue", a 1969 song written by Shel Silverstein and made famous by Johnny Cash.

Background

"Dot" was recorded with the rest of Percolater at Chapman Recording Studios in Kansas City, Missouri and at Nightingale Studio in Nashville, Tennessee. Stevenson and guitarist Stephen Egerton served as record producers and additional recording engineers. The recordings were mixed by John Hampton at Ardent Studios in Memphis, Tennessee. "Can't Say" and "A Boy Named Sue" were also recorded during the Percolater sessions but were left off of the album. "Dot" was released through Cruz Records in 1992 as a 10-inch single, cassette single, and CD single.

The music video for "Dot" shows the band members performing the song on a set made to resemble the interior of a house, with Reynolds using various props related to the song's lyrics such as a telescope, telephone, and mirror. Stevenson did not think "Dot" was the strongest choice of song for a music video. Reynolds later recalled that "When we went to record the 'Dot' video, it was really apparent that Bill was dissatisfied. He wasn't happy". "At that point I was idealizing we would put our foot forward visually with a song that maybe had more of an eighth note drive to it," said Stevenson, "but on that record I didn't have really any good songs, so it's like 'Okay, a lot of lip from you, Stevenson. Where's your good song?' And it's like 'I don’t have any.'"