So I’ve been off my game for a while. Work’s been crazy and it seems like I surprisingly lost steam after my trip to SELF. Go figure. Regardless, let’s get back into the study game. On tap today is managing the time settings on your RHEL server.
Your timezone information is detailed at /etc/localtime. However, this is really just a symlink to the actual info as shown here:
lrwxrwxrwx. 1 root root 38 Sep 2 15:11 /etc/localtime -> ../usr/share/zoneinfo/America/New_York
The timedatectl utility can be used not only to display your current settings (timezone, NTP, etc.) but also to make adjustments.
# timedatectl Local time: Thu 2016-09-15 20:32:33 EDT Universal time: Fri 2016-09-16 00:32:33 UTC RTC time: Fri 2016-09-16 00:32:32 Time zone: America/New_York (EDT, -0400) NTP enabled: yes NTP synchronized: yes RTC in local TZ: no DST active: yes Last DST change: DST began at Sun 2016-03-13 01:59:59 EST Sun 2016-03-13 03:00:00 EDT Next DST change: DST ends (the clock jumps one hour backwards) at Sun 2016-11-06 01:59:59 EDT Sun 2016-11-06 01:00:00 EST
Changing Your Timezone
There are a couple of ways you can change your timezone. If you know your timezone you can use the timedatectrl utility directly. If you’re not sure, you can get a listing of available timezones by running:
timedatectl list-timezones
Africa/Abidjan Africa/Accra Africa/Addis_Ababa Africa/Algiers Africa/Asmara ..... America/Nassau America/New_York America/Nipigon America/Nome America/Noronha America/North_Dakota/Beulah America/North_Dakota/Center America/North_Dakota/New_Salem
Since I’m on the US East coast my timezone is “America/New_York”. Just pass the timezone to the utility with the set-timezone function:
timedatectl set-timezone America/New_YorkIf you don’t remember how to use the utility, there is an easy way to walk through a “wizard” using the tzselect utility. Simply answer the questions and your timezone will be updated correctly.
Please identify a location so that time zone rules can be set correctly. Please select a continent or ocean. 1) Africa 2) Americas 3) Antarctica 4) Arctic Ocean 5) Asia 6) Atlantic Ocean 7) Australia 8) Europe 9) Indian Ocean 10) Pacific Ocean 11) none - I want to specify the time zone using the Posix TZ format. #? 2 Please select a country. 1) Anguilla 19) Dominican Republic 37) Peru 2) Antigua & Barbuda 20) Ecuador 38) Puerto Rico 3) Argentina 21) El Salvador 39) St Barthelemy 4) Aruba 22) French Guiana 40) St Kitts & Nevis 5) Bahamas 23) Greenland 41) St Lucia 6) Barbados 24) Grenada 42) St Maarten (Dutch) 7) Belize 25) Guadeloupe 43) St Martin (French) 8) Bolivia 26) Guatemala 44) St Pierre & Miquelon 9) Brazil 27) Guyana 45) St Vincent 10) Canada 28) Haiti 46) Suriname 11) Caribbean NL 29) Honduras 47) Trinidad & Tobago 12) Cayman Islands 30) Jamaica 48) Turks & Caicos Is 13) Chile 31) Martinique 49) United States 14) Colombia 32) Mexico 50) Uruguay 15) Costa Rica 33) Montserrat 51) Venezuela 16) Cuba 34) Nicaragua 52) Virgin Islands (UK) 17) Curacao 35) Panama 53) Virgin Islands (US) 18) Dominica 36) Paraguay #? 49 Please select one of the following time zone regions. 1) Eastern (most areas) 16) Central - ND (Morton rural) 2) Eastern - MI (most areas) 17) Central - ND (Mercer) 3) Eastern - KY (Louisville area) 18) Mountain (most areas) 4) Eastern - KY (Wayne) 19) Mountain - ID (south); OR (east) 5) Eastern - IN (most areas) 20) MST - Arizona (except Navajo) 6) Eastern - IN (Da, Du, K, Mn) 21) Pacific 7) Eastern - IN (Pulaski) 22) Alaska (most areas) 8) Eastern - IN (Crawford) 23) Alaska - Juneau area 9) Eastern - IN (Pike) 24) Alaska - Sitka area 10) Eastern - IN (Switzerland) 25) Alaska - Annette Island 11) Central (most areas) 26) Alaska - Yakutat 12) Central - IN (Perry) 27) Alaska (west) 13) Central - IN (Starke) 28) Aleutian Islands 14) Central - MI (Wisconsin border) 29) Hawaii 15) Central - ND (Oliver) #? 5 The following information has been given: United States Eastern - IN (most areas) Therefore TZ='America/Indiana/Indianapolis' will be used. Local time is now: Thu Sep 15 20:50:04 EDT 2016. Universal Time is now: Fri Sep 16 00:50:04 UTC 2016. Is the above information OK? 1) Yes 2) No
It looks like I made the wrong choices. Whoops. Good thing it asks me to confirm! 🙂
What if you realize that the clock is wrong?
Changing the Time
Use the format “2016-09-15 20:54:00” and pass it to the timedatectl utility.
timedatectl set-time "2016-09-15 20:54:00"You can also pass the time without the date.
Note: If you try this with NTP enabled you’ll receive an error. So let’s take care of that, too.
Failed to set time: Automatic time synchronization is enabled
Disable Time Synchronization
timedatectl set-ntp false NTP enabled: no NTP synchronized: yes
Note that after making these adjustments your time will all be local and there won’t be any synchronization occurring.
NTP enabled: no NTP synchronized: no
We’ll talk about managing time servers in another post.