tzfile(5) File Formats Manual tzfile(5) tzfile - tzset(3) /usr/share/zoneinfo. RFC 9636. 8 . (bigendian ) 0 () 1 (). 44 : o ASCII "TZif" . o ( 2021 ASCII NUL "2", "3", "4"). o . o : tzh_ttisutcnt (UT)/ . (UT .) tzh_ttisstdcnt / . tzh_leapcnt . tzh_timecnt . tzh_typecnt ( ). tzh_charcnt . : o tzh_timecnt . . ( time(2)) . o tzh_timecnt - - ( ). ( TZ .) . o ttinfo tzh_typecnt : struct ttinfo { int32_t tt_utoff; unsigned char tt_isdst; unsigned char tt_desigidx; }; tt_utoff tt_isdst tt_desigidx. tt_utoff tt_isdst tm_isdst localtime(3) tt_desigidx ttinfo "-00" ttinfo . tt_utoff -2**31 32 . tt_utoff [-89999, 93599] ( -25 26 ) POSIX [-24:59:59, 25:59:59]. o tzh_charcnt (null) tt_desigidx . . . o tzh_leapcnt ( time(2)) . . . . 1 -1 . 1 -1 ( ). o tzh_ttisstdcnt / ( ). o tzh_ttisutcnt / . / / . / / TZif TZ . TZ="EET-2EEST" TZif "EET-2EEST" TZif "posixrules" "Europe/Brussels" . POSIX 2037 ( ) TZ="Europe/Athens" TZ="EET-2EEST,M3.5.0/3,M10.5.0/4" POSIX.1-2017 . localtime(3) ttinfo tzh_timecnt . 2 2 . ( .) TZ . TZ ( ) . TZ "WET0WEST,M3.5.0/1,M10.5.0" "WEST" . TZ TZif. 0 ( ). 3 3 TZ ( newtzset(3)) POSIX.1-2024 POSIX.1-2017: TZ="<-02>2<-01>,M3.5.0/-1,M10.5.0/0" -167 167 0 24. TZ="XXX3EDT4,0/0,J365/23" 1 00:00 31 24:00 . 4 TZif 4 +1 -1 TZif . . . 1 2038. 1 1. 1 . 4 . 4 3 TZ . 1 2 . 1 . tzh_timecnt 1 . TZif TZif ( ). (3) ASCII (6) "-", "+". POSIX . UT. "+0530" UT UT 5.5 "-00" UT . 2 1 . . . UTC 60 60 59 UTC. TZif. TZif . : o TZif TZif o TZif TZif o TZif. TZif TZif TZif . . . TZif : o 1 . 1. 1 2 32 . o 2 3 POSIX.1-2024 POSIX.1-2017 TZ . 2. o UT TZ . TZ . o 2 24:00 - TZ "EST5EDT,0/0,J365/25" (-04). "XXX3EDT4,0/0,J365/23" (XXX, -03) (EDT, -04) . - "AST4" (-04). o 2 3 RFC 9636 4 . o . . o TZ . TZ="Africa/Casablanca". TZif 2087 TZ "<+01>-1", . o 0 0. ( ) . o -2**31. 32- 64- 32 . -2**31. o 64- . -2**59. o TZ "<" ">". "<" ">" . o ASCII. . o 3 6 ASCII "-", "+". . o TZif UT UT . TZ "IST-1GMT0,M10.5.0,M3.5.0/1", (IST, +01) (GMT, +00) . TZ "GMT0IST,M3.5.0/1,M10.5.0", . UT . o UTC 60 . UTC +01:23:45 78796801 (1972-06-30 23:59:60 UTC) 78796800 78796801 01:23:45 01:23:46 78796815 01:23:59 01:23:60. UTC 1972. . o . 1970. o . . o "-08" "+", "-", . o (UT) -12 +12 . o (UT) [-3599, -1] 3600 0 "+00". o (UT) 15 . time(2) localtime(3) tzset(3) tzselect(8) zdump(8) zic(8). Olson A, Eggert P, Murchison K. (TZif). 2024. Internet RFC 9636 doi:10.17487/RFC9636 . 3 . . : . tzfile(5)