Configure localtime. dpkg-reconfigure tzdata

Question

I'm using this to configure localtime:

dpkg-reconfigure tzdata 

It is ncurses interface. I'm looking for the way to programming this. Is there true way without user ncurses interface?

How to change localtime by one shell command?

Solution 1

I'm assuming you want to change the timezone by one shell command.

Do you have timedatectl on your system?

If so:

timedatectl status will show your current settings.

timedatectl list-timezones shows available timezones.

timedatectl set-timezone Antarctica/Mawson sets it.

Note: If the RTC is configured to be in the local time, this will also update the RTC time.

Solution 2

Is there true way without user ncurses interface?

echo Antarctica/Mawson >/etc/timezone
dpkg-reconfigure -f noninteractive tzdata

Yes, you can create one shell command:

sh -c 'echo Antarctica/Mawson >/etc/timezone && dpkg-reconfigure -f noninteractive tzdata'

:)

There is a bug in tzdata: certain values get normalized by dpkg-reconfigure:

echo 'US/Central' >/etc/timezone
dpkg-reconfigure -f noninteractive tzdata
# Current default time zone: 'America/Chicago'

echo 'US/Eastern' >/etc/timezone
apt-get install --reinstall tzdata
# Current default time zone: 'America/New_York'

Solution 3

None of the answers here worked for me. What worked for me was running:

printf "%s\n"                                              \
       "tzdata  tzdata/Areas    select America"            \
       "tzdata  tzdata/Zones/America    select New_York"   \
       | debconf-set-selections

After doing this, when you can now trigger

DEBIAN_FRONTEND=noninteractive apt-get install -y tzdata

and it will automatically use the correct time zone based on the pre-loaded settings.

Solution 4

The way that I'm taking everytime:

# /bin/ln -fs /usr/share/zoneinfo/Asia/Novosibirsk /etc/localtime

It working pretty everywhere, from Linux to BSD family.

Solution 5

When you have interactive commands it's always an option to use expect program:

#!/usr/bin/expect -f
set timeout 360
spawn dpkg-reconfigure tzdata

expect "Geographic area:"

send -- "2\r"

expect "city or region"

send -- "134\r"

This will look for the string in stdout "expect" and then send the string in "send" to stdin.

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Comments

[Admin]

This question has an up-to-date answer on ServerFault.

[Gilles 'SO- stop being evil']

Where's timedatectl from? apt-file search timedatectl returns nothing on Debian stable.

[garethTheRed]

timedatectl is available from the systemd-services package on Ubuntu and from systemd on Fedora

[Evgeny Vereshchagin]

dpkg-reconfigure tzdata updates /etc/timezone. openjdk uses /etc/timezone before /etc/localtime to guess the local timezone. see The algorithm that OpenJDK uses to guess the local timezone ID on Linux.

[Evgeny Vereshchagin]

see also: unix.stackexchange.com/a/16294/120177

[Evgeny Vereshchagin]

cron uses /etc/timezone for TZ setting.

[Evgeny Vereshchagin]

On Debian dpkg-reconfigure makes copy, timedatectl makes copy. See timedated doesn't support split-usr, uses a symlink for /etc/localtime, Useless systemd-timedated /etc/localtime symlink complain in syslog

[Joó Ádám]

In 16.04 you have to set /etc/localtime, dpkg-reconfigure then updates /etc/timezone: bugs.launchpad.net/ubuntu/+source/tzdata/+bug/1554806

[YudhiWidyatama]

this one works under docker, timedatectl does not.

[Hakanai]

Hmm. Failed to create bus connection: No such file or directory

[Dave T.]

I upvote this because the apt install --reinstall tzdata fixed my date problems. Even after adjusting /etc/localtime and /etc/timezone either by hand or using the various tz* commands (including dpkg-reconfigure) left the date in a weird state (showed as local time being the same as UTC but timezone was "America" not "PDT")

[We Are All Monica]

I also had to do /etc/init.d/cron restart in order for cron jobs to start running under the new timezone.

[Patrick Taylor]

It's worth noting that if your app doesn't use stdout/stdin then this solution won't help. However in the OPs actual use case this should do.