![\"Unix](\"\/wp-content\/uploads\/2020\/01\/1b3a3bdeb0400f3b34d5cd6964a48010.jpg\")
<\/p>\nViti 2020 \u00ebsht\u00eb nj\u00eb vit i r\u00ebnd\u00ebsish\u00ebm p\u00ebr Unix: n\u00eb fillim t\u00eb vitit, sistemi origjinal operativ mbushi 50 vjet. Koha Unix, e njohur gjithashtu si \u00abdata e epok\u00ebs\u00bb, \u00ebsht\u00eb numri i sekondave t\u00eb kaluara q\u00eb nga 1 janari 1970. Por \u00e7far\u00eb e shqet\u00ebson zhvilluesin e b\u00ebrtham\u00ebs p\u00ebr p\u00ebrvjetorin gjysm\u00eb shekullor t\u00eb Unix-it?<\/p>\n
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Megjith\u00ebse disa nga zhvillimet e hershme t\u00eb Unix-it i paraprijn\u00eb fillimit zyrtar t\u00eb \u00abepok\u00ebs\u00bb s\u00eb tij, 1 janari 1970 mbetet pika zero n\u00eb koh\u00eb p\u00ebr POSIX. Prandaj, me fillimin e 1 janarit 2020, platforma zyrtarisht mbushi 50 vjet.<\/p>\n
Koha <\/strong>Unix kundrejt koh\u00ebs njer\u00ebzore<\/strong><\/p>\n Nga pik\u00ebpamja e koh\u00ebs njer\u00ebzore, 50 vjet \u00ebsht\u00eb nj\u00eb periudh\u00eb e madhe. Nga k\u00ebndv\u00ebshtrimi i koh\u00ebs Unix, nuk ka asgj\u00eb t\u00eb ve\u00e7ant\u00eb n\u00eb 50 vjet, nd\u00ebrsa 43 vjet do t\u00eb ishin po aq t\u00eb r\u00ebnd\u00ebsishme. Sistemet Unix (p\u00ebrfshir\u00eb Linux) ruajn\u00eb vlerat e dat\u00ebs dhe or\u00ebs si numrin e sekondave t\u00eb kaluara q\u00eb nga 1970-01-01 00:00:00 UTC, duke u regjistruar n\u00eb 32 bita. P\u00ebr t\u00eb p\u00ebrcaktuar sa sekonda kan\u00eb kaluar nga at\u00ebher\u00eb dhe, p\u00ebr rrjedhoj\u00eb, vlera aktuale e koh\u00ebs Unix, mund t\u00eb ekzekutoni komand\u00ebn:<\/p>\n $ date +%s<\/p>\n 1576883876<\/p>\n Argumenti %s pas komand\u00ebs date p\u00ebrcakton shfaqjen e dat\u00ebs dhe or\u00ebs aktuale n\u00eb form\u00ebn e numrit t\u00eb sekondave q\u00eb nga fillimi i 1970-01-01.<\/p>\n Cila \u00ebsht\u00eb data maksimale q\u00eb mund t\u00eb ruajn\u00eb sistemet <\/strong>Unix?<\/strong><\/p>\n P\u00ebr t\u00eb kuptuar sa koh\u00eb mund t\u00eb p\u00ebrmbajn\u00eb sistemet Unix, duhet t\u00eb vler\u00ebsoni kapacitetin e fush\u00ebs 32-bit. Kjo mund t\u00eb llogaritet k\u00ebshtu:<\/p>\n $ echo '2^32' | bc<\/p>\n 4294967296<\/p>\n Megjithat\u00eb, duke pasur parasysh se Unix parashikon ruajtjen e shifrave negative, nj\u00eb bit \u00ebsht\u00eb rezervuar p\u00ebr shenj\u00ebn, duke e reduktuar, k\u00ebshtu, vler\u00ebn e koh\u00ebs n\u00eb:<\/p>\n $ echo '2^31' | bc<\/p>\n 2147483648<\/p>\n Dhe pasi num\u00ebrimi Unix fillon nga 0, kjo do t\u00eb thot\u00eb se kemi 2 147 483 648 vlera, por e madhja \u00ebsht\u00eb 2 147 483 647 - vlera datore dhe orare Unix nuk mund t\u00eb kaloj\u00eb k\u00ebt\u00eb num\u00ebr. Ashtu si odometri n\u00eb nj\u00eb makin\u00eb nuk mund t\u00eb tregoj\u00eb m\u00eb shum\u00eb se 999 999 kilometra - shtoni 1 dhe vlera do t\u00eb zerohet.<\/p>\n Sa zgjat nj\u00eb vit n\u00eb sekonda?<\/strong><\/p>\n Numri i sekondave n\u00eb nj\u00eb vit mund t\u00eb llogaritet k\u00ebshtu:<\/p>\n $ expr 24 * 60 * 60 * 365<\/p>\n 31536000<\/p>\n N\u00eb nj\u00eb vit t\u00eb prishur, shtohet nj\u00eb dit\u00eb m\u00eb shum\u00eb:<\/p>\n $ expr 24 * 60 * 60 * 366<\/p>\n 31622400<\/p>\n Si e shfaq Unix dit\u00eblindjen e tij t\u00eb 50-t\u00eb?<\/strong><\/p>\n M\u00eb 1 janar 2020 n\u00eb or\u00ebn 12:00 do t\u00eb jet\u00eb koha 1577836800. Llogaritja \u00ebsht\u00eb pak m\u00eb e komplikuar, sepse duhet t\u00eb merret n\u00eb konsiderat\u00eb vitet e prishura. Q\u00eb nga fillimi i epok\u00ebs Unix, kan\u00eb qen\u00eb 12 t\u00eb till\u00eb, duke filluar nga viti 1972 deri n\u00eb vitin 2016. K\u00ebshtu, kan\u00eb kaluar 38 vite normale.<\/p>\n K\u00ebtu \u00ebsht\u00eb si duket ekipi expr p\u00ebr t\u00eb llogaritur sekondat e kaluara gjat\u00eb 50 viteve:<\/p>\n $ expr 24 * 60 * 60 * 365 * 38 + 24 * 60 * 60 * 366 * 12<\/p>\n 1577836800<\/p>\n Ose k\u00ebshtu, duke marr\u00eb parasysh llogaritjet e m\u00ebparshme:<\/p>\n $ expr 31536000 * 38 + 31622400 * 12<\/p>\n 1577836800<\/p>\n Ky m\u00ebnyr\u00eb e regjistrimit t\u00eb koh\u00ebs e b\u00ebri sistemet Unix t\u00eb paprekshme ndaj problemit Y2K, p\u00ebr t\u00eb cilin njer\u00ebzit n\u00eb fund t\u00eb vitit 1999 ishin t\u00eb shqet\u00ebsuar se kalimi n\u00eb vitin 2000 mund t\u00eb d\u00ebmtonte sistemet kompjuterike. V\u00ebshtir\u00ebsit\u00eb ishin shum\u00eb m\u00eb pak se sa pritej. Faktikisht, vet\u00ebm aplikacionet q\u00eb regjistronin vitet n\u00eb format dyshifror u p\u00ebrball\u00ebn me problematik\u00ebn e shfaqjes s\u00eb datave t\u00eb reja. Shum\u00eb zhvillues b\u00ebn\u00eb pun\u00eb shtes\u00eb p\u00ebr t\u00eb garantuar q\u00eb aplikacionet e tyre nuk do t\u00eb preken nga problemi Y2K.<\/p>\n Kur do <\/strong>Unix t\u00eb has\u00eb probleme?<\/strong><\/p>\n V\u00ebshtir\u00ebsi t\u00eb ngjashme pritet t\u00eb p\u00ebrballen sistemet Unix jo p\u00ebrpara vitit 2038, kur datat e ruajtura n\u00eb formatin e p\u00ebrshkruar m\u00eb par\u00eb do t\u00eb tejkalojn\u00eb hap\u00ebsir\u00ebn 32-bit. Ka ende 18 vjet, por zhvilluesit e kernelit tashm\u00eb po punojn\u00eb p\u00ebr t\u00eb shmangur d\u00ebshtimet e ardhshme.<\/p>\n Problemi i vitit 2038 ndonj\u00ebher\u00eb p\u00ebrmendet si problemi Y2K38. N\u00ebse kjo nuk zgjidhet deri t\u00eb mart\u00ebn, m\u00eb 19 janar 2038, pas k\u00ebsaj date sistemet mund t\u00eb mendojn\u00eb se kemi nj\u00eb vit 1901. Nj\u00eb nga m\u00ebnyrat p\u00ebr t\u00eb zgjidhur k\u00ebt\u00eb problem \u00ebsht\u00eb t\u00eb kalojm\u00eb n\u00eb nj\u00eb paraqitje 64-bit t\u00eb informacionit p\u00ebr dat\u00ebn dhe or\u00ebn. Disa mendojn\u00eb se kjo do t\u00eb jet\u00eb shum\u00eb m\u00eb e komplikuar se sa duket.<\/p>\n![\"Unix](\"\/wp-content\/uploads\/2020\/01\/aba69e769edb987923b060b6e32f9a00.jpg\")
<\/p>\n![\"Unix](\"\/wp-content\/uploads\/2020\/01\/a720be1bfca58df09540785bf66f556d.jpg\")
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