settimezone - Configuración de la zona horaria en UTC(0) en PHP

timezone america buenos aires

Question

¿Por qué funciona esto?

date_default_timezone_set(''Australia/Currie'');

Pero esto no parece tener ningún efecto en absoluto?

date_default_timezone_set(''UTC'');

Este valor no cambia al configurar la zona horaria a UTC:

echo date(''Y-m-d H:i:s'', time());

Estoy usando php 5.2.13, y la zona horaria de mi servidor es:

$server_tz = date_default_timezone_get();
echo $server_tz; //outputs ''America/Guayaquil''

Este es el código original:

echo time() . "<br>/n";
date_default_timezone_set(''UTC'');
echo time() . "<br>/n";

Salida:

1317235130
1317235130

Answer 1

Lista de zonas horarias completas disponibles.

$time_zones = array (
  0 => ''Africa/Abidjan'',
  1 => ''Africa/Accra'',
  2 => ''Africa/Addis_Ababa'',
  3 => ''Africa/Algiers'',
  4 => ''Africa/Asmara'',
  5 => ''Africa/Asmera'',
  6 => ''Africa/Bamako'',
  7 => ''Africa/Bangui'',
  8 => ''Africa/Banjul'',
  9 => ''Africa/Bissau'',
  10 => ''Africa/Blantyre'',
  11 => ''Africa/Brazzaville'',
  12 => ''Africa/Bujumbura'',
  13 => ''Africa/Cairo'',
  14 => ''Africa/Casablanca'',
  15 => ''Africa/Ceuta'',
  16 => ''Africa/Conakry'',
  17 => ''Africa/Dakar'',
  18 => ''Africa/Dar_es_Salaam'',
  19 => ''Africa/Djibouti'',
  20 => ''Africa/Douala'',
  21 => ''Africa/El_Aaiun'',
  22 => ''Africa/Freetown'',
  23 => ''Africa/Gaborone'',
  24 => ''Africa/Harare'',
  25 => ''Africa/Johannesburg'',
  26 => ''Africa/Juba'',
  27 => ''Africa/Kampala'',
  28 => ''Africa/Khartoum'',
  29 => ''Africa/Kigali'',
  30 => ''Africa/Kinshasa'',
  31 => ''Africa/Lagos'',
  32 => ''Africa/Libreville'',
  33 => ''Africa/Lome'',
  34 => ''Africa/Luanda'',
  35 => ''Africa/Lubumbashi'',
  36 => ''Africa/Lusaka'',
  37 => ''Africa/Malabo'',
  38 => ''Africa/Maputo'',
  39 => ''Africa/Maseru'',
  40 => ''Africa/Mbabane'',
  41 => ''Africa/Mogadishu'',
  42 => ''Africa/Monrovia'',
  43 => ''Africa/Nairobi'',
  44 => ''Africa/Ndjamena'',
  45 => ''Africa/Niamey'',
  46 => ''Africa/Nouakchott'',
  47 => ''Africa/Ouagadougou'',
  48 => ''Africa/Porto-Novo'',
  49 => ''Africa/Sao_Tome'',
  50 => ''Africa/Timbuktu'',
  51 => ''Africa/Tripoli'',
  52 => ''Africa/Tunis'',
  53 => ''Africa/Windhoek'',
  54 => ''America/Adak'',
  55 => ''America/Anchorage'',
  56 => ''America/Anguilla'',
  57 => ''America/Antigua'',
  58 => ''America/Araguaina'',
  59 => ''America/Argentina/Buenos_Aires'',
  60 => ''America/Argentina/Catamarca'',
  61 => ''America/Argentina/ComodRivadavia'',
  62 => ''America/Argentina/Cordoba'',
  63 => ''America/Argentina/Jujuy'',
  64 => ''America/Argentina/La_Rioja'',
  65 => ''America/Argentina/Mendoza'',
  66 => ''America/Argentina/Rio_Gallegos'',
  67 => ''America/Argentina/Salta'',
  68 => ''America/Argentina/San_Juan'',
  69 => ''America/Argentina/San_Luis'',
  70 => ''America/Argentina/Tucuman'',
  71 => ''America/Argentina/Ushuaia'',
  72 => ''America/Aruba'',
  73 => ''America/Asuncion'',
  74 => ''America/Atikokan'',
  75 => ''America/Atka'',
  76 => ''America/Bahia'',
  77 => ''America/Bahia_Banderas'',
  78 => ''America/Barbados'',
  79 => ''America/Belem'',
  80 => ''America/Belize'',
  81 => ''America/Blanc-Sablon'',
  82 => ''America/Boa_Vista'',
  83 => ''America/Bogota'',
  84 => ''America/Boise'',
  85 => ''America/Buenos_Aires'',
  86 => ''America/Cambridge_Bay'',
  87 => ''America/Campo_Grande'',
  88 => ''America/Cancun'',
  89 => ''America/Caracas'',
  90 => ''America/Catamarca'',
  91 => ''America/Cayenne'',
  92 => ''America/Cayman'',
  93 => ''America/Chicago'',
  94 => ''America/Chihuahua'',
  95 => ''America/Coral_Harbour'',
  96 => ''America/Cordoba'',
  97 => ''America/Costa_Rica'',
  98 => ''America/Creston'',
  99 => ''America/Cuiaba'',
  100 => ''America/Curacao'',
  101 => ''America/Danmarkshavn'',
  102 => ''America/Dawson'',
  103 => ''America/Dawson_Creek'',
  104 => ''America/Denver'',
  105 => ''America/Detroit'',
  106 => ''America/Dominica'',
  107 => ''America/Edmonton'',
  108 => ''America/Eirunepe'',
  109 => ''America/El_Salvador'',
  110 => ''America/Ensenada'',
  111 => ''America/Fort_Nelson'',
  112 => ''America/Fort_Wayne'',
  113 => ''America/Fortaleza'',
  114 => ''America/Glace_Bay'',
  115 => ''America/Godthab'',
  116 => ''America/Goose_Bay'',
  117 => ''America/Grand_Turk'',
  118 => ''America/Grenada'',
  119 => ''America/Guadeloupe'',
  120 => ''America/Guatemala'',
  121 => ''America/Guayaquil'',
  122 => ''America/Guyana'',
  123 => ''America/Halifax'',
  124 => ''America/Havana'',
  125 => ''America/Hermosillo'',
  126 => ''America/Indiana/Indianapolis'',
  127 => ''America/Indiana/Knox'',
  128 => ''America/Indiana/Marengo'',
  129 => ''America/Indiana/Petersburg'',
  130 => ''America/Indiana/Tell_City'',
  131 => ''America/Indiana/Vevay'',
  132 => ''America/Indiana/Vincennes'',
  133 => ''America/Indiana/Winamac'',
  134 => ''America/Indianapolis'',
  135 => ''America/Inuvik'',
  136 => ''America/Iqaluit'',
  137 => ''America/Jamaica'',
  138 => ''America/Jujuy'',
  139 => ''America/Juneau'',
  140 => ''America/Kentucky/Louisville'',
  141 => ''America/Kentucky/Monticello'',
  142 => ''America/Knox_IN'',
  143 => ''America/Kralendijk'',
  144 => ''America/La_Paz'',
  145 => ''America/Lima'',
  146 => ''America/Los_Angeles'',
  147 => ''America/Louisville'',
  148 => ''America/Lower_Princes'',
  149 => ''America/Maceio'',
  150 => ''America/Managua'',
  151 => ''America/Manaus'',
  152 => ''America/Marigot'',
  153 => ''America/Martinique'',
  154 => ''America/Matamoros'',
  155 => ''America/Mazatlan'',
  156 => ''America/Mendoza'',
  157 => ''America/Menominee'',
  158 => ''America/Merida'',
  159 => ''America/Metlakatla'',
  160 => ''America/Mexico_City'',
  161 => ''America/Miquelon'',
  162 => ''America/Moncton'',
  163 => ''America/Monterrey'',
  164 => ''America/Montevideo'',
  165 => ''America/Montreal'',
  166 => ''America/Montserrat'',
  167 => ''America/Nassau'',
  168 => ''America/New_York'',
  169 => ''America/Nipigon'',
  170 => ''America/Nome'',
  171 => ''America/Noronha'',
  172 => ''America/North_Dakota/Beulah'',
  173 => ''America/North_Dakota/Center'',
  174 => ''America/North_Dakota/New_Salem'',
  175 => ''America/Ojinaga'',
  176 => ''America/Panama'',
  177 => ''America/Pangnirtung'',
  178 => ''America/Paramaribo'',
  179 => ''America/Phoenix'',
  180 => ''America/Port-au-Prince'',
  181 => ''America/Port_of_Spain'',
  182 => ''America/Porto_Acre'',
  183 => ''America/Porto_Velho'',
  184 => ''America/Puerto_Rico'',
  185 => ''America/Rainy_River'',
  186 => ''America/Rankin_Inlet'',
  187 => ''America/Recife'',
  188 => ''America/Regina'',
  189 => ''America/Resolute'',
  190 => ''America/Rio_Branco'',
  191 => ''America/Rosario'',
  192 => ''America/Santa_Isabel'',
  193 => ''America/Santarem'',
  194 => ''America/Santiago'',
  195 => ''America/Santo_Domingo'',
  196 => ''America/Sao_Paulo'',
  197 => ''America/Scoresbysund'',
  198 => ''America/Shiprock'',
  199 => ''America/Sitka'',
  200 => ''America/St_Barthelemy'',
  201 => ''America/St_Johns'',
  202 => ''America/St_Kitts'',
  203 => ''America/St_Lucia'',
  204 => ''America/St_Thomas'',
  205 => ''America/St_Vincent'',
  206 => ''America/Swift_Current'',
  207 => ''America/Tegucigalpa'',
  208 => ''America/Thule'',
  209 => ''America/Thunder_Bay'',
  210 => ''America/Tijuana'',
  211 => ''America/Toronto'',
  212 => ''America/Tortola'',
  213 => ''America/Vancouver'',
  214 => ''America/Virgin'',
  215 => ''America/Whitehorse'',
  216 => ''America/Winnipeg'',
  217 => ''America/Yakutat'',
  218 => ''America/Yellowknife'',
  219 => ''Antarctica/Casey'',
  220 => ''Antarctica/Davis'',
  221 => ''Antarctica/DumontDUrville'',
  222 => ''Antarctica/Macquarie'',
  223 => ''Antarctica/Mawson'',
  224 => ''Antarctica/McMurdo'',
  225 => ''Antarctica/Palmer'',
  226 => ''Antarctica/Rothera'',
  227 => ''Antarctica/South_Pole'',
  228 => ''Antarctica/Syowa'',
  229 => ''Antarctica/Troll'',
  230 => ''Antarctica/Vostok'',
  231 => ''Arctic/Longyearbyen'',
  232 => ''Asia/Aden'',
  233 => ''Asia/Almaty'',
  234 => ''Asia/Amman'',
  235 => ''Asia/Anadyr'',
  236 => ''Asia/Aqtau'',
  237 => ''Asia/Aqtobe'',
  238 => ''Asia/Ashgabat'',
  239 => ''Asia/Ashkhabad'',
  240 => ''Asia/Baghdad'',
  241 => ''Asia/Bahrain'',
  242 => ''Asia/Baku'',
  243 => ''Asia/Bangkok'',
  244 => ''Asia/Beirut'',
  245 => ''Asia/Bishkek'',
  246 => ''Asia/Brunei'',
  247 => ''Asia/Calcutta'',
  248 => ''Asia/Chita'',
  249 => ''Asia/Choibalsan'',
  250 => ''Asia/Chongqing'',
  251 => ''Asia/Chungking'',
  252 => ''Asia/Colombo'',
  253 => ''Asia/Dacca'',
  254 => ''Asia/Damascus'',
  255 => ''Asia/Dhaka'',
  256 => ''Asia/Dili'',
  257 => ''Asia/Dubai'',
  258 => ''Asia/Dushanbe'',
  259 => ''Asia/Gaza'',
  260 => ''Asia/Harbin'',
  261 => ''Asia/Hebron'',
  262 => ''Asia/Ho_Chi_Minh'',
  263 => ''Asia/Hong_Kong'',
  264 => ''Asia/Hovd'',
  265 => ''Asia/Irkutsk'',
  266 => ''Asia/Istanbul'',
  267 => ''Asia/Jakarta'',
  268 => ''Asia/Jayapura'',
  269 => ''Asia/Jerusalem'',
  270 => ''Asia/Kabul'',
  271 => ''Asia/Kamchatka'',
  272 => ''Asia/Karachi'',
  273 => ''Asia/Kashgar'',
  274 => ''Asia/Kathmandu'',
  275 => ''Asia/Katmandu'',
  276 => ''Asia/Khandyga'',
  277 => ''Asia/Kolkata'',
  278 => ''Asia/Krasnoyarsk'',
  279 => ''Asia/Kuala_Lumpur'',
  280 => ''Asia/Kuching'',
  281 => ''Asia/Kuwait'',
  282 => ''Asia/Macao'',
  283 => ''Asia/Macau'',
  284 => ''Asia/Magadan'',
  285 => ''Asia/Makassar'',
  286 => ''Asia/Manila'',
  287 => ''Asia/Muscat'',
  288 => ''Asia/Nicosia'',
  289 => ''Asia/Novokuznetsk'',
  290 => ''Asia/Novosibirsk'',
  291 => ''Asia/Omsk'',
  292 => ''Asia/Oral'',
  293 => ''Asia/Phnom_Penh'',
  294 => ''Asia/Pontianak'',
  295 => ''Asia/Pyongyang'',
  296 => ''Asia/Qatar'',
  297 => ''Asia/Qyzylorda'',
  298 => ''Asia/Rangoon'',
  299 => ''Asia/Riyadh'',
  300 => ''Asia/Saigon'',
  301 => ''Asia/Sakhalin'',
  302 => ''Asia/Samarkand'',
  303 => ''Asia/Seoul'',
  304 => ''Asia/Shanghai'',
  305 => ''Asia/Singapore'',
  306 => ''Asia/Srednekolymsk'',
  307 => ''Asia/Taipei'',
  308 => ''Asia/Tashkent'',
  309 => ''Asia/Tbilisi'',
  310 => ''Asia/Tehran'',
  311 => ''Asia/Tel_Aviv'',
  312 => ''Asia/Thimbu'',
  313 => ''Asia/Thimphu'',
  314 => ''Asia/Tokyo'',
  315 => ''Asia/Ujung_Pandang'',
  316 => ''Asia/Ulaanbaatar'',
  317 => ''Asia/Ulan_Bator'',
  318 => ''Asia/Urumqi'',
  319 => ''Asia/Ust-Nera'',
  320 => ''Asia/Vientiane'',
  321 => ''Asia/Vladivostok'',
  322 => ''Asia/Yakutsk'',
  323 => ''Asia/Yekaterinburg'',
  324 => ''Asia/Yerevan'',
  325 => ''Atlantic/Azores'',
  326 => ''Atlantic/Bermuda'',
  327 => ''Atlantic/Canary'',
  328 => ''Atlantic/Cape_Verde'',
  329 => ''Atlantic/Faeroe'',
  330 => ''Atlantic/Faroe'',
  331 => ''Atlantic/Jan_Mayen'',
  332 => ''Atlantic/Madeira'',
  333 => ''Atlantic/Reykjavik'',
  334 => ''Atlantic/South_Georgia'',
  335 => ''Atlantic/St_Helena'',
  336 => ''Atlantic/Stanley'',
  337 => ''Australia/ACT'',
  338 => ''Australia/Adelaide'',
  339 => ''Australia/Brisbane'',
  340 => ''Australia/Broken_Hill'',
  341 => ''Australia/Canberra'',
  342 => ''Australia/Currie'',
  343 => ''Australia/Darwin'',
  344 => ''Australia/Eucla'',
  345 => ''Australia/Hobart'',
  346 => ''Australia/LHI'',
  347 => ''Australia/Lindeman'',
  348 => ''Australia/Lord_Howe'',
  349 => ''Australia/Melbourne'',
  350 => ''Australia/North'',
  351 => ''Australia/NSW'',
  352 => ''Australia/Perth'',
  353 => ''Australia/Queensland'',
  354 => ''Australia/South'',
  355 => ''Australia/Sydney'',
  356 => ''Australia/Tasmania'',
  357 => ''Australia/Victoria'',
  358 => ''Australia/West'',
  359 => ''Australia/Yancowinna'',
  360 => ''Europe/Amsterdam'',
  361 => ''Europe/Andorra'',
  362 => ''Europe/Athens'',
  363 => ''Europe/Belfast'',
  364 => ''Europe/Belgrade'',
  365 => ''Europe/Berlin'',
  366 => ''Europe/Bratislava'',
  367 => ''Europe/Brussels'',
  368 => ''Europe/Bucharest'',
  369 => ''Europe/Budapest'',
  370 => ''Europe/Busingen'',
  371 => ''Europe/Chisinau'',
  372 => ''Europe/Copenhagen'',
  373 => ''Europe/Dublin'',
  374 => ''Europe/Gibraltar'',
  375 => ''Europe/Guernsey'',
  376 => ''Europe/Helsinki'',
  377 => ''Europe/Isle_of_Man'',
  378 => ''Europe/Istanbul'',
  379 => ''Europe/Jersey'',
  380 => ''Europe/Kaliningrad'',
  381 => ''Europe/Kiev'',
  382 => ''Europe/Lisbon'',
  383 => ''Europe/Ljubljana'',
  384 => ''Europe/London'',
  385 => ''Europe/Luxembourg'',
  386 => ''Europe/Madrid'',
  387 => ''Europe/Malta'',
  388 => ''Europe/Mariehamn'',
  389 => ''Europe/Minsk'',
  390 => ''Europe/Monaco'',
  391 => ''Europe/Moscow'',
  392 => ''Europe/Nicosia'',
  393 => ''Europe/Oslo'',
  394 => ''Europe/Paris'',
  395 => ''Europe/Podgorica'',
  396 => ''Europe/Prague'',
  397 => ''Europe/Riga'',
  398 => ''Europe/Rome'',
  399 => ''Europe/Samara'',
  400 => ''Europe/San_Marino'',
  401 => ''Europe/Sarajevo'',
  402 => ''Europe/Simferopol'',
  403 => ''Europe/Skopje'',
  404 => ''Europe/Sofia'',
  405 => ''Europe/Stockholm'',
  406 => ''Europe/Tallinn'',
  407 => ''Europe/Tirane'',
  408 => ''Europe/Tiraspol'',
  409 => ''Europe/Uzhgorod'',
  410 => ''Europe/Vaduz'',
  411 => ''Europe/Vatican'',
  412 => ''Europe/Vienna'',
  413 => ''Europe/Vilnius'',
  414 => ''Europe/Volgograd'',
  415 => ''Europe/Warsaw'',
  416 => ''Europe/Zagreb'',
  417 => ''Europe/Zaporozhye'',
  418 => ''Europe/Zurich'',
  419 => ''Indian/Antananarivo'',
  420 => ''Indian/Chagos'',
  421 => ''Indian/Christmas'',
  422 => ''Indian/Cocos'',
  423 => ''Indian/Comoro'',
  424 => ''Indian/Kerguelen'',
  425 => ''Indian/Mahe'',
  426 => ''Indian/Maldives'',
  427 => ''Indian/Mauritius'',
  428 => ''Indian/Mayotte'',
  429 => ''Indian/Reunion'',
  430 => ''Pacific/Apia'',
  431 => ''Pacific/Auckland'',
  432 => ''Pacific/Bougainville'',
  433 => ''Pacific/Chatham'',
  434 => ''Pacific/Chuuk'',
  435 => ''Pacific/Easter'',
  436 => ''Pacific/Efate'',
  437 => ''Pacific/Enderbury'',
  438 => ''Pacific/Fakaofo'',
  439 => ''Pacific/Fiji'',
  440 => ''Pacific/Funafuti'',
  441 => ''Pacific/Galapagos'',
  442 => ''Pacific/Gambier'',
  443 => ''Pacific/Guadalcanal'',
  444 => ''Pacific/Guam'',
  445 => ''Pacific/Honolulu'',
  446 => ''Pacific/Johnston'',
  447 => ''Pacific/Kiritimati'',
  448 => ''Pacific/Kosrae'',
  449 => ''Pacific/Kwajalein'',
  450 => ''Pacific/Majuro'',
  451 => ''Pacific/Marquesas'',
  452 => ''Pacific/Midway'',
  453 => ''Pacific/Nauru'',
  454 => ''Pacific/Niue'',
  455 => ''Pacific/Norfolk'',
  456 => ''Pacific/Noumea'',
  457 => ''Pacific/Pago_Pago'',
  458 => ''Pacific/Palau'',
  459 => ''Pacific/Pitcairn'',
  460 => ''Pacific/Pohnpei'',
  461 => ''Pacific/Ponape'',
  462 => ''Pacific/Port_Moresby'',
  463 => ''Pacific/Rarotonga'',
  464 => ''Pacific/Saipan'',
  465 => ''Pacific/Samoa'',
  466 => ''Pacific/Tahiti'',
  467 => ''Pacific/Tarawa'',
  468 => ''Pacific/Tongatapu'',
  469 => ''Pacific/Truk'',
  470 => ''Pacific/Wake'',
  471 => ''Pacific/Wallis'',
  472 => ''Pacific/Yap'',
  473 => ''Brazil/Acre'',
  474 => ''Brazil/DeNoronha'',
  475 => ''Brazil/East'',
  476 => ''Brazil/West'',
  477 => ''Canada/Atlantic'',
  478 => ''Canada/Central'',
  479 => ''Canada/East-Saskatchewan'',
  480 => ''Canada/Eastern'',
  481 => ''Canada/Mountain'',
  482 => ''Canada/Newfoundland'',
  483 => ''Canada/Pacific'',
  484 => ''Canada/Saskatchewan'',
  485 => ''Canada/Yukon'',
  486 => ''CET'',
  487 => ''Chile/Continental'',
  488 => ''Chile/EasterIsland'',
  489 => ''CST6CDT'',
  490 => ''Cuba'',
  491 => ''EET'',
  492 => ''Egypt'',
  493 => ''Eire'',
  494 => ''EST'',
  495 => ''EST5EDT'',
  496 => ''Etc/GMT'',
  497 => ''Etc/GMT+0'',
  498 => ''Etc/GMT+1'',
  499 => ''Etc/GMT+10'',
  500 => ''Etc/GMT+11'',
  501 => ''Etc/GMT+12'',
  502 => ''Etc/GMT+2'',
  503 => ''Etc/GMT+3'',
  504 => ''Etc/GMT+4'',
  505 => ''Etc/GMT+5'',
  506 => ''Etc/GMT+6'',
  507 => ''Etc/GMT+7'',
  508 => ''Etc/GMT+8'',
  509 => ''Etc/GMT+9'',
  510 => ''Etc/GMT-0'',
  511 => ''Etc/GMT-1'',
  512 => ''Etc/GMT-10'',
  513 => ''Etc/GMT-11'',
  514 => ''Etc/GMT-12'',
  515 => ''Etc/GMT-13'',
  516 => ''Etc/GMT-14'',
  517 => ''Etc/GMT-2'',
  518 => ''Etc/GMT-3'',
  519 => ''Etc/GMT-4'',
  520 => ''Etc/GMT-5'',
  521 => ''Etc/GMT-6'',
  522 => ''Etc/GMT-7'',
  523 => ''Etc/GMT-8'',
  524 => ''Etc/GMT-9'',
  525 => ''Etc/GMT0'',
  526 => ''Etc/Greenwich'',
  527 => ''Etc/UCT'',
  528 => ''Etc/Universal'',
  529 => ''Etc/UTC'',
  530 => ''Etc/Zulu'',
  531 => ''Factory'',
  532 => ''GB'',
  533 => ''GB-Eire'',
  534 => ''GMT'',
  535 => ''GMT+0'',
  536 => ''GMT-0'',
  537 => ''GMT0'',
  538 => ''Greenwich'',
  539 => ''Hongkong'',
  540 => ''HST'',
  541 => ''Iceland'',
  542 => ''Iran'',
  543 => ''Israel'',
  544 => ''Jamaica'',
  545 => ''Japan'',
  546 => ''Kwajalein'',
  547 => ''Libya'',
  548 => ''MET'',
  549 => ''Mexico/BajaNorte'',
  550 => ''Mexico/BajaSur'',
  551 => ''Mexico/General'',
  552 => ''MST'',
  553 => ''MST7MDT'',
  554 => ''Navajo'',
  555 => ''NZ'',
  556 => ''NZ-CHAT'',
  557 => ''Poland'',
  558 => ''Portugal'',
  559 => ''PRC'',
  560 => ''PST8PDT'',
  561 => ''ROC'',
  562 => ''ROK'',
  563 => ''Singapore'',
  564 => ''Turkey'',
  565 => ''UCT'',
  566 => ''Universal'',
  567 => ''US/Alaska'',
  568 => ''US/Aleutian'',
  569 => ''US/Arizona'',
  570 => ''US/Central'',
  571 => ''US/East-Indiana'',
  572 => ''US/Eastern'',
  573 => ''US/Hawaii'',
  574 => ''US/Indiana-Starke'',
  575 => ''US/Michigan'',
  576 => ''US/Mountain'',
  577 => ''US/Pacific'',
  578 => ''US/Pacific-New'',
  579 => ''US/Samoa'',
  580 => ''UTC'',
  581 => ''W-SU'',
  582 => ''WET'',
  583 => ''Zulu'',
)

Answer 2

¿''UTC'' es un identificador de zona horaria válido en su sistema?

<?php
if (date_default_timezone_set(''UTC'')){
    echo "UTC is a valid time zone";
}else{
    echo "The system doesn''t know WTFUTC.  Maybe try updating tzinfo with your package manager?";
}

Answer 3

El problema es que está mostrando time() , que es una marca de tiempo UNIX basada en GMT / UTC. Es por eso que no cambia. date() por otro lado, formatea la hora según esa marca de tiempo.

Una marca de tiempo es la cantidad de segundos desde la Época Unix (1 de enero de 1970 a las 00:00:00 GMT).

echo date(''Y-m-d H:i:s T'', time()) . "<br>/n";
date_default_timezone_set(''UTC'');
echo date(''Y-m-d H:i:s T'', time()) . "<br>/n";

Answer 4

UTC es definitivamente una zona horaria válida. Es simplemente una abreviación de Tiempo Universal Coordinado. Además, recuerde que date_default_timezone_set acepta uno de los siguientes valores:

    $timezones=array(
    "America/Adak",
    "America/Argentina/Buenos_Aires",
    "America/Argentina/La_Rioja",
    "America/Argentina/San_Luis",
    "America/Atikokan",
    "America/Belem",
    "America/Boise",
    "America/Caracas",
    "America/Chihuahua",
    "America/Cuiaba",
    "America/Denver",
    "America/El_Salvador",
    "America/Godthab",
    "America/Guatemala",
    "America/Hermosillo",
    "America/Indiana/Tell_City",
    "America/Inuvik",
    "America/Kentucky/Louisville",
    "America/Lima",
    "America/Managua",
    "America/Mazatlan",
    "America/Mexico_City",
    "America/Montreal",
    "America/Nome",
    "America/Ojinaga",
    "America/Port-au-Prince",
    "America/Rainy_River",
    "America/Rio_Branco",
    "America/Santo_Domingo",
    "America/St_Barthelemy",
    "America/St_Vincent",
    "America/Tijuana",
    "America/Whitehorse",
    "America/Anchorage",
    "America/Argentina/Catamarca",
    "America/Argentina/Mendoza",
    "America/Argentina/Tucuman",
    "America/Atka",
    "America/Belize",
    "America/Buenos_Aires",
    "America/Catamarca",
    "America/Coral_Harbour",
    "America/Curacao",
    "America/Detroit",
    "America/Ensenada",
    "America/Goose_Bay",
    "America/Guayaquil",
    "America/Indiana/Indianapolis",
    "America/Indiana/Vevay",
    "America/Iqaluit",
    "America/Kentucky/Monticello",
    "America/Los_Angeles",
    "America/Manaus",
    "America/Mendoza",
    "America/Miquelon",
    "America/Montserrat",
    "America/Noronha",
    "America/Panama",
    "America/Port_of_Spain",
    "America/Rankin_Inlet",
    "America/Rosario",
    "America/Sao_Paulo",
    "America/St_Johns",
    "America/Swift_Current",
    "America/Toronto",
    "America/Winnipeg",
    "America/Anguilla",
    "America/Argentina/ComodRivadavia",
    "America/Argentina/Rio_Gallegos",
    "America/Argentina/Ushuaia",
    "America/Bahia",
    "America/Blanc-Sablon",
    "America/Cambridge_Bay",
    "America/Cayenne",
    "America/Cordoba",
    "America/Danmarkshavn",
    "America/Dominica",
    "America/Fort_Wayne",
    "America/Grand_Turk",
    "America/Guyana",
    "America/Indiana/Knox",
    "America/Indiana/Vincennes",
    "America/Jamaica",
    "America/Knox_IN",
    "America/Louisville",
    "America/Marigot",
    "America/Menominee",
    "America/Moncton",
    "America/Nassau",
    "America/North_Dakota/Beulah",
    "America/Pangnirtung",
    "America/Porto_Acre",
    "America/Recife",
    "America/Santa_Isabel",
    "America/Scoresbysund",
    "America/St_Kitts",
    "America/Tegucigalpa",
    "America/Tortola",
    "America/Yakutat",
    "America/Antigua",
    "America/Argentina/Cordoba",
    "America/Argentina/Salta",
    "America/Aruba",
    "America/Bahia_Banderas",
    "America/Boa_Vista",
    "America/Campo_Grande",
    "America/Cayman",
    "America/Costa_Rica",
    "America/Dawson",
    "America/Edmonton",
    "America/Fortaleza",
    "America/Grenada",
    "America/Halifax",
    "America/Indiana/Marengo",
    "America/Indiana/Winamac",
    "America/Jujuy",
    "America/Kralendijk",
    "America/Lower_Princes",
    "America/Martinique",
    "America/Merida",
    "America/Monterrey",
    "America/New_York",
    "America/North_Dakota/Center",
    "America/Paramaribo",
    "America/Porto_Velho",
    "America/Regina",
    "America/Santarem",
    "America/Shiprock",
    "America/St_Lucia",
    "America/Thule",
    "America/Vancouver",
    "America/Yellowknife",
    "America/Araguaina",
    "America/Argentina/Jujuy",
    "America/Argentina/San_Juan",
    "America/Asuncion",
    "America/Barbados",
    "America/Bogota",
    "America/Cancun",
    "America/Chicago",
    "America/Creston",
    "America/Dawson_Creek",
    "America/Eirunepe",
    "America/Glace_Bay",
    "America/Guadeloupe",
    "America/Havana",
    "America/Indiana/Petersburg",
    "America/Indianapolis",
    "America/Juneau",
    "America/La_Paz",
    "America/Maceio",
    "America/Matamoros",
    "America/Metlakatla",
    "America/Montevideo",
    "America/Nipigon",
    "America/North_Dakota/New_Salem",
    "America/Phoenix",
    "America/Puerto_Rico",
    "America/Resolute",
    "America/Santiago",
    "America/Sitka",
    "America/St_Thomas",
    "America/Thunder_Bay",
    "America/Virgin",
    "Indian/Antananarivo",
    "Indian/Kerguelen",
    "Indian/Reunion",
    "Australia/ACT",
    "Australia/Currie",
    "Australia/Lindeman",
    "Australia/Perth",
    "Australia/Victoria",
    "Europe/Amsterdam",
    "Europe/Berlin",
    "Europe/Chisinau",
    "Europe/Helsinki",
    "Europe/Kiev",
    "Europe/Madrid",
    "Europe/Moscow",
    "Europe/Prague",
    "Europe/Sarajevo",
    "Europe/Tallinn",
    "Europe/Vatican",
    "Europe/Zagreb",
    "Pacific/Apia",
    "Pacific/Efate",
    "Pacific/Galapagos",
    "Pacific/Johnston",
    "Pacific/Marquesas",
    "Pacific/Noumea",
    "Pacific/Ponape",
    "Pacific/Tahiti",
    "Pacific/Wallis",
    "Indian/Chagos",
    "Indian/Mahe",
    "Australia/Adelaide",
    "Australia/Darwin",
    "Australia/Lord_Howe",
    "Australia/Queensland",
    "Australia/West",
    "Europe/Andorra",
    "Europe/Bratislava",
    "Europe/Copenhagen",
    "Europe/Isle_of_Man",
    "Europe/Lisbon",
    "Europe/Malta",
    "Europe/Nicosia",
    "Europe/Riga",
    "Europe/Simferopol",
    "Europe/Tirane",
    "Europe/Vienna",
    "Europe/Zaporozhye",
    "Pacific/Auckland",
    "Pacific/Enderbury",
    "Pacific/Gambier",
    "Pacific/Kiritimati",
    "Pacific/Midway",
    "Pacific/Pago_Pago",
    "Pacific/Port_Moresby",
    "Pacific/Tarawa",
    "Pacific/Yap",
    "Africa/Abidjan",
    "Africa/Asmera",
    "Africa/Blantyre",
    "Africa/Ceuta",
    "Africa/Douala",
    "Africa/Johannesburg",
    "Africa/Kinshasa",
    "Africa/Lubumbashi",
    "Africa/Mbabane",
    "Africa/Niamey",
    "Africa/Timbuktu",
    "Africa/Accra",
    "Africa/Bamako",
    "Africa/Brazzaville",
    "Africa/Conakry",
    "Africa/El_Aaiun",
    "Africa/Juba",
    "Africa/Lagos",
    "Africa/Lusaka",
    "Africa/Mogadishu",
    "Africa/Nouakchott",
    "Africa/Tripoli",
    "Africa/Addis_Ababa",
    "Africa/Bangui",
    "Africa/Bujumbura",
    "Africa/Dakar",
    "Africa/Freetown",
    "Africa/Kampala",
    "Africa/Libreville",
    "Africa/Malabo",
    "Africa/Monrovia",
    "Africa/Ouagadougou",
    "Africa/Tunis",
    "Africa/Algiers",
    "Africa/Banjul",
    "Africa/Cairo",
    "Africa/Dar_es_Salaam",
    "Africa/Gaborone",
    "Africa/Khartoum",
    "Africa/Lome",
    "Africa/Maputo",
    "Africa/Nairobi",
    "Africa/Porto-Novo",
    "Africa/Windhoek",
    "Africa/Asmara",
    "Africa/Bissau",
    "Africa/Casablanca",
    "Africa/Djibouti",
    "Africa/Harare",
    "Africa/Kigali",
    "Africa/Luanda",
    "Africa/Maseru",
    "Africa/Ndjamena",
    "Africa/Sao_Tome",
    "Atlantic/Azores",
    "Atlantic/Faroe",
    "Atlantic/St_Helena",
    "Atlantic/Bermuda",
    "Atlantic/Jan_Mayen",
    "Atlantic/Stanley",
    "Atlantic/Canary",
    "Atlantic/Madeira",
    "Atlantic/Cape_Verde",
    "Atlantic/Reykjavik",
    "Atlantic/Faeroe",
    "Atlantic/South_Georgia",
    "Asia/Aden",
    "Asia/Aqtobe",
    "Asia/Baku",
    "Asia/Calcutta",
    "Asia/Dacca",
    "Asia/Dushanbe",
    "Asia/Hong_Kong",
    "Asia/Jayapura",
    "Asia/Kashgar",
    "Asia/Kuala_Lumpur",
    "Asia/Magadan",
    "Asia/Novokuznetsk",
    "Asia/Pontianak",
    "Asia/Riyadh",
    "Asia/Shanghai",
    "Asia/Tehran",
    "Asia/Ujung_Pandang",
    "Asia/Vladivostok",
    "Asia/Almaty",
    "Asia/Ashgabat",
    "Asia/Bangkok",
    "Asia/Choibalsan",
    "Asia/Damascus",
    "Asia/Gaza",
    "Asia/Hovd",
    "Asia/Jerusalem",
    "Asia/Kathmandu",
    "Asia/Kuching",
    "Asia/Makassar",
    "Asia/Novosibirsk",
    "Asia/Pyongyang",
    "Asia/Saigon",
    "Asia/Singapore",
    "Asia/Tel_Aviv",
    "Asia/Ulaanbaatar",
    "Asia/Yakutsk",
    "Asia/Amman",
    "Asia/Ashkhabad",
    "Asia/Beirut",
    "Asia/Chongqing",
    "Asia/Dhaka",
    "Asia/Harbin",
    "Asia/Irkutsk",
    "Asia/Kabul",
    "Asia/Katmandu",
    "Asia/Kuwait",
    "Asia/Manila",
    "Asia/Omsk",
    "Asia/Qatar",
    "Asia/Sakhalin",
    "Asia/Taipei",
    "Asia/Thimbu",
    "Asia/Ulan_Bator",
    "Asia/Yekaterinburg",
    "Asia/Anadyr",
    "Asia/Baghdad",
    "Asia/Bishkek",
    "Asia/Chungking",
    "Asia/Dili",
    "Asia/Hebron",
    "Asia/Istanbul",
    "Asia/Kamchatka",
    "Asia/Kolkata",
    "Asia/Macao",
    "Asia/Muscat",
    "Asia/Oral",
    "Asia/Qyzylorda",
    "Asia/Samarkand",
    "Asia/Tashkent",
    "Asia/Thimphu",
    "Asia/Urumqi",
    "Asia/Yerevan",
    "Asia/Aqtau",
    "Asia/Bahrain",
    "Asia/Brunei",
    "Asia/Colombo",
    "Asia/Dubai",
    "Asia/Ho_Chi_Minh",
    "Asia/Jakarta",
    "Asia/Karachi",
    "Asia/Krasnoyarsk",
    "Asia/Macau",
    "Asia/Nicosia",
    "Asia/Phnom_Penh",
    "Asia/Rangoon",
    "Asia/Seoul",
    "Asia/Tbilisi",
    "Asia/Tokyo",
    "Asia/Vientiane",
    "Australia/Canberra",
    "Australia/LHI",
    "Australia/NSW",
    "Australia/Tasmania",
    "Australia/Broken_Hill",
    "Australia/Hobart",
    "Australia/North",
    "Australia/Sydney",
    "Pacific/Chuuk",
    "Pacific/Fiji",
    "Pacific/Guam",
    "Pacific/Kwajalein",
    "Pacific/Niue",
    "Pacific/Pitcairn",
    "Pacific/Saipan",
    "Pacific/Truk",
    "Pacific/Chatham",
    "Pacific/Fakaofo",
    "Pacific/Guadalcanal",
    "Pacific/Kosrae",
    "Pacific/Nauru",
    "Pacific/Palau",
    "Pacific/Rarotonga",
    "Pacific/Tongatapu",
    "Pacific/Easter",
    "Pacific/Funafuti",
    "Pacific/Honolulu",
    "Pacific/Majuro",
    "Pacific/Norfolk",
    "Pacific/Pohnpei",
    "Pacific/Samoa",
    "Pacific/Wake",
    "Antarctica/Casey",
    "Antarctica/McMurdo",
    "Antarctica/Vostok",
    "Antarctica/Davis",
    "Antarctica/Palmer",
    "Antarctica/DumontDUrville",
    "Antarctica/Rothera",
    "Antarctica/Macquarie",
    "Antarctica/South_Pole",
    "Antarctica/Mawson",
    "Antarctica/Syowa",
    "Arctic/Longyearbyen",
    "Europe/Athens",
    "Europe/Brussels",
    "Europe/Dublin",
    "Europe/Istanbul",
    "Europe/Ljubljana",
    "Europe/Mariehamn",
    "Europe/Oslo",
    "Europe/Rome",
    "Europe/Skopje",
    "Europe/Tiraspol",
    "Europe/Vilnius",
    "Europe/Zurich",
    "Europe/Belfast",
    "Europe/Bucharest",
    "Europe/Gibraltar",
    "Europe/Jersey",
    "Europe/London",
    "Europe/Minsk",
    "Europe/Paris",
    "Europe/Samara",
    "Europe/Sofia",
    "Europe/Uzhgorod",
    "Europe/Volgograd",
    "Europe/Belgrade",
    "Europe/Budapest",
    "Europe/Guernsey",
    "Europe/Kaliningrad",
    "Europe/Luxembourg",
    "Europe/Monaco",
    "Europe/Podgorica",
    "Europe/San_Marino",
    "Europe/Stockholm",
    "Europe/Vaduz",
    "Europe/Warsaw",
    "Indian/Cocos",
    "Indian/Mauritius",
    "Indian/Christmas",
    "Indian/Maldives",
    "Indian/Comoro",
    "Indian/Mayotte",
    "Australia/Brisbane",
    "Australia/Eucla",
    "Australia/Melbourne",
    "Australia/South",
    "Australia/Yancowinna",
    );

Zonas horarias en PHP en http://www.php.net/manual/en/timezones.php