Ndikupepesa .
Dzulo Ndinafunsa za zinthu zosangalatsa za nthawi ya Unix, ndipo ndinakumbukira kuti nthawi zina zimagwira ntchito mopanda nzeru.
Mfundo zitatu izi zikuwoneka zomveka komanso zomveka, sichoncho?
- Unix nthawi ndi chiwerengero cha masekondi kuyambira January 1, 1970 00:00:00 UTC.
- Ngati mudikirira ndendende sekondi imodzi, nthawi ya Unix idzasintha ndi sekondi imodzi ndendende.
- Nthawi ya Unix simabwerera kumbuyo.
Palibe mwa izi chomwe chiri chowona.
Koma sikokwanira kungonena kuti, βPalibe chimene chili choona,β popanda kufotokoza. bwanji. Onani pansipa kuti mumve zambiri. Koma ngati mukufuna kudziganizira nokha, musapitirire chithunzi cha wotchiyo!
Table wotchi kuyambira 1770s. Yopangidwa ndi John Leroux. Kuchokera . Lofalitsidwa ndi chilolezo
Malingaliro onse atatu olakwika ali ndi chifukwa chimodzi: . Ngati simukuzidziwa za leap seconds, nayi mawu ofulumira:
Nthawi ya UTC imatsimikiziridwa ndi zinthu ziwiri:
- : Avereji yowerengera kuchokera mazana a mawotchi a atomiki padziko lonse lapansi. Tikhoza kuyeza chachiwiri ndi mphamvu ya maginito ya atomu, ndipo uku ndiko kuyeza kolondola kwambiri kwa nthawi kodziwika ndi sayansi.
- , kutengera kuzungulira kwa Dziko lapansi mozungulira mozungulira. Kusintha kumodzi kwathunthu ndi tsiku limodzi.
Vuto ndilakuti manambala awiriwa samafanana nthawi zonse. Kuzungulira kwa dziko lapansi sikofanana - kumachepetsa pang'onopang'ono, kotero kuti masiku a Universal Time amakhala otalikirapo. Kumbali ina, mawotchi a atomiki ndi olondola mwaudyerekezi ndipo sasintha kwa zaka mamiliyoni ambiri.
Nthawi ziwiri zikapanda kulunzanitsa, sekondi imawonjezedwa kapena kuchotsedwa ku UTC kuti iwabwezeretse kulumikizana. Kuyambira 1972 utumiki (omwe amayendetsa nkhaniyi) adawonjezera masekondi 27 owonjezera. Zotsatira zake zinali masiku 27 a UTC okhala ndi masekondi 86. Mwachidziwitso, tsiku lokhala ndi masekondi 401 (kuchotsa limodzi) ndizotheka. Zosankha zonsezi zimatsutsana ndi lingaliro lofunikira la nthawi ya Unix.
Nthawi ya Unix imaganiza kuti tsiku lililonse limatenga masekondi 86 ndendende (400 Γ 60 Γ 60 = 24), popanda masekondi ena owonjezera. Ngati kulumpha kotereku kumachitika, ndiye kuti nthawi ya Unix imadumpha sekondi imodzi, kapena kuwerengera masekondi awiri m'modzi. Pofika 86, ikusowa masekondi 400 odumphadumpha.
Chifukwa chake malingaliro athu olakwika ayenera kuwonjezeredwa motere:
- Unix nthawi ndi chiwerengero cha masekondi kuyambira January 1, 1970 00:00:00 UTC kuchotseratu masekondi.
- Ngati mudikirira sekondi imodzi ndendende, nthawi ya Unix isintha ndi sekondi imodzi ndendende, pokhapokha ngati leap yachiwiri yachotsedwa.
Mpaka pano, masekondi sanachotsedwepo mwachizoloΕ΅ezi (ndipo kuchepetsa kuzungulira kwa Dziko lapansi kumatanthauza kuti sizingatheke), koma ngati zidzachitika, zikutanthauza kuti tsiku la UTC lidzakhala lalifupi lachiwiri. Pankhaniyi, sekondi yomaliza ya UTC (23:59:59) imatayidwa.
Tsiku lililonse la Unix liri ndi nambala yofanana ya masekondi, kotero sekondi yomaliza ya Unix ya tsiku lofupikitsidwa silingafanane ndi nthawi iliyonse ya UTC. Izi ndi momwe zimawonekera, pakapita kotala-sekondi:
Mukayamba pa 23:59:58:00 UTC ndikudikirira mphindi imodzi, nthawi ya Unix idzapititsa patsogolo masekondi awiri a UTC ndipo chizindikiro cha Unix 101 sichidzaperekedwa kwa aliyense. - Nthawi ya Unix singabwerere m'mbuyo, mpaka kamphindi kakang'ono kawonjezedwa.
Izi zachitika kale nthawi 27 muzochita. Kumapeto kwa tsiku la UTC, sekondi yowonjezera imawonjezedwa ku 23:59:60. Unix ili ndi chiwerengero chofanana cha masekondi pa tsiku, kotero sichingawonjezere sekondi yowonjezera - m'malo mwake iyenera kubwereza maulendo a Unix pamphindi yomaliza. Izi ndi momwe zimawonekera, pakapita kotala-sekondi:
Mukayamba pa 23:59:60.50 ndikudikirira theka la sekondi, nthawi ya Unix amabwerera ndi theka la sekondi, ndipo chizindikiro cha Unix 101 chikufanana ndi masekondi awiri a UTC.
Izi mwina sizinthu zokhazokha za nthawi za Unix - zomwe ndidakumbukira dzulo.
Nthawi - kwambiri chinthu chachilendo.
Source: www.habr.com