Date (Unix command): Difference between revisions

Revision as of 17:14, 1 April 2025

Revision as of 18:34, 1 April 2025

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==Option flags==

*+"''date format codes"'' Alters the output using the specified date conversion codes which are prefaced with at % sign. <ref name=KerriskLocaleKerrisk>{{cite web |last=Kerrisk |first=Michael |date=Feb 2, 2025 |title=date(1) — Linux manual page |url=https://man7.org/linux/man-pages/man1/date.1.html |access-date=Mar 20, 2025 |website=man7.org |publisher=}}</ref> date +"Today is day %j of the year %Y and it’s a %A"

Output: Today is day 078 of the year 2025 and it’s a Wednesday

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The value corresponds assigned to LC_TIME refers to files found in /usr/share/i18/locale. The file name is usually of the form languageCode_countryCode where the codes are the two character ISO codes for [[language|List of ISO 639 language codes]] or [[country|List of ISO 3166 country codes6]] <ref>{{cite web| author=<!-- not stated --> |title=Locale Environment Variables: Locale Names |url=https://www.gnu.org/software/gettext/manual/html_node/Locale-Names.html|website=www.gnu.org |publisher=gnu.org |access-date=Mar 20, 2025}}</ref>

It is also possible to change the date presentation format by setting the environment variables LANG or LC_ALL however these will also change other presentation formats such as LC_MESSAGE (command error messages) and LC_MONETARY which many not be desirable.<ref name=KerriskLocaleKerrisk></ref>

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The directory /usr/share/zoneinfo contains a large group of [[tz database| timezone database files|]] files describing both current and historical definitions of local times to facilitate the correct reproduction and translation of time information from one time zone and era to another. The files keep track of the offset from Greenwich Mean Time as well as when seasonal adjustments have been scheduled to take place such as the transition to and from [[Daylight saving time|Daylight Saving Time]] (DST). <ref>{{cite book |last=Ward |first=Brian |date=April 19, 2021 |title=How Linux Works, 3rd Edition |publisher=No Starch Press |section=7.5.1 |isbn=978-1718-500402}} </ref>

==History==

David McKenzie is the author of the Linux version of date. The date command has been part of Unix since AT&T's original Version 1.<ref name=Kerrisk /><ref>{{cite web |author=<!-- not stated --> |date=Sept 10, 2024 |title=FreeBSD Manual Pages |url=https://man.freebsd.org/cgi/man.cgi?date |website=man.freebsd.org |access-date=Apr 1, 2025}} </ref>

==References==