How do I find out the current time for each zone name specified on the command line on a Linux, FreeBSD, OS X or Unix-like system? How do I report time zone information for Singapore or Japan on the command line?

 

You can use the zdump command to see the current time for each zone name specified on the command line.

How do I find a list of all zone name?

The standard time zone directory is located at the following location:

AIX, Solaris, HP-UX – /usr/share/lib/zoneinfo/

OS X, FreeBSD, OpenBSD, NetBSD – /usr/share/zoneinfo/

Linux – /usr/share/zoneinfo/

Cd to above directory to see a time zone database file:

$ cd /usr/share/zoneinfo/

$ ls -l

$ ls -l | more

-$ ls

 

Sample outputs:

+VERSION Australia EET  Factory  Greenwich Jamaica  Mexico  Poland  US  posixrules

Africa  Brazil  EST  GB  HST  Japan  NZ  Portugal UTC  zone.tab

America  CET  EST5EDT  GB-Eire  Hongkong Kwajalein NZ-CHAT  ROC  Universal

Antarctica CST6CDT  Egypt  GMT  Iceland  Libya  Navajo  ROK  W-SU

Arctic  Canada  Eire  GMT+0  Indian  MET  PRC  Singapore WET

Asia  Chile  Etc  GMT-0  Iran  MST  PST8PDT  Turkey  Zulu

Atlantic Cuba  Europe  GMT0  Israel  MST7MDT  Pacific  UCT  iso3166.tab

You can cd into directory such as Asia, Europe, or America to get more detailed information:

$ cd America

-$ ls

 

Sample outputs:

Adak  Blanc-Sablon Cordoba  Fort_Nelson Indiana  Maceio  Montevideo Port_of_Spain Sao_Paulo Toronto

Anchorage Boa_Vista Costa_Rica Fort_Wayne Indianapolis Managua  Montreal Porto_Acre Scoresbysund Tortola

Anguilla Bogota  Creston  Fortaleza Inuvik  Manaus  Montserrat Porto_Velho Shiprock Vancouver

Antigua  Boise  Cuiaba  Glace_Bay Iqaluit  Marigot  Nassau  Puerto_Rico Sitka  Virgin

Araguaina Buenos_Aires Curacao  Godthab  Jamaica  Martinique New_York Rainy_River St_Barthelemy Whitehorse

Argentina Cambridge_Bay Danmarkshavn Goose_Bay Jujuy  Matamoros Nipigon  Rankin_Inlet St_Johns Winnipeg

Aruba  Campo_Grande Dawson  Grand_Turk Juneau  Mazatlan Nome  Recife  St_Kitts Yakutat

Asuncion Cancun  Dawson_Creek Grenada  Kentucky Mendoza  Noronha  Regina  St_Lucia Yellowknife

Atikokan Caracas  Denver  Guadeloupe Knox_IN  Menominee North_Dakota Resolute St_Thomas

Atka  Catamarca Detroit  Guatemala Kralendijk Merida  Ojinaga  Rio_Branco St_Vincent

Bahia  Cayenne  Dominica Guayaquil La_Paz  Metlakatla Panama  Rosario  Swift_Current

Bahia_Banderas Cayman  Edmonton Guyana  Lima  Mexico_City Pangnirtung Santa_Isabel Tegucigalpa

Barbados Chicago  Eirunepe Halifax  Los_Angeles Miquelon Paramaribo Santarem Thule

Belem  Chihuahua El_Salvador Havana  Louisville Moncton  Phoenix  Santiago Thunder_Bay

Belize  Coral_Harbour Ensenada Hermosillo Lower_Princes Monterrey Port-au-Prince Santo_Domingo Tijuana

How do I see time zone information for given country/zone name?

To see time zone information for Singapore , enter:

$ zdump Singapore

 

To see time zone information for Japan, enter:

$ zdump Japan

 

To see time zone information for Iceland, enter:

$ zdump Iceland

 

To see time zone information for Perth (AU), enter:

$ zdump Australia/Perth

 

To see time zone information for India, enter:

$ zdump Asia/Kolkata

 

To see time zone information for New York , enter:

$ zdump America/New_York

 

Sample outputs:

Fig.01: zdump Linux and Unix command in action

How to use bash for loop to see current time in different zones?

Say your cloud server located in 4 different time zone and you want to know the current time for techsupport purpose:

for t in America/New_York Australia/Perth Japan Asia/Kolkata ; do   zdump $t; done

Sample outputs:

America/New_York  Wed Dec 30 12:03:23 2015 EST

Australia/Perth  Thu Dec 31 01:03:23 2015 AWST

Japan  Thu Dec 31 02:03:23 2015 JST

Asia/Kolkata  Wed Dec 30 22:33:23 2015 IST

Be verbose

You can pass the -v option to zdump command. From the man page:

For each zonename on the command line, print the time at the lowest possible time value, the time one day after the lowest possible time value, the times both one second before and exactly at each detected time discontinuity, the time at one day less than the highest possible time value, and the time at the highest possible time value, Each line ends with isdst=1 if the given time is Daylight Saving Time or isdst=0 otherwise.

Try the following command:

$ zdump -v Japan

 

Sample outputs:

Japan  Fri Dec 13 20:45:52 1901 UTC = Sat Dec 14 05:45:52 1901 JCST isdst=0

Japan  Sat Dec 14 20:45:52 1901 UTC = Sun Dec 15 05:45:52 1901 JCST isdst=0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

How to cut off the verbose output

You can also pass the -c cutoffyear option to cut off the verbose output near the start of the given year. For example, to see verbose time zone information for Japan with verbose output stopping near the start of the year 2035, enter:

$ zdump -v -c 2035 Japan