Timezone

Timezone set on Linux

Timezone tells your system where you are in the world depending on your exact location on this planet with GMT-/+<time> format.

On most Linux,

/etc/timezone is a text-based representation of what timezone you are in.

/etc/localtime is a binary representation of the exact rules for calculating the time relative to UNIX time by a symbolic link from /etc/localtime to a file in the /usr/share/zoneinfo directory.

instead of manually chaing those file, timedatectl command change your timezone much easily.

# Get available timezone list and it's name 
$ timedatectl list-timezones  | grep -i seoul
Asia/Seoul

# Set system timezone to Asia/Seoul, for example.
$ sudo timedatectl set-timezone Asia/Seoul
$ ls -al /etc/timezone
-rw-r--r-- 1 root root 11 May 30 10:51 /etc/timezone

$ cat /etc/timezone
Asia/Seoul

$ ls -al /etc/localtime
lrwxrwxrwx 1 root root 32 May 30 10:51 /etc/localtime -> ../usr/share/zoneinfo/Asia/Seoul

systemd-timesyncd

systemd uses /etc/systemd/timesyncd.conf file for NTP time sync.

FallbackNTP points to the NTP servers, for example, FallbackNTP=time.nist.gov

# changing configuration file needs to restart systemd-timesyncd service
# timedatectl show-timesync command to verify current status.

#To enable the network time synchronization
%sudo timedatectl set-ntp true

#To disable the network time sync
$sudo timedatectl set-ntp false