How do I set the date format to ISO globally in Linux?

Question

I would like to globally set the Linux date format to ISO, which looks roughly like this:

YYYY-MM-DD HH:MM:SS
2009-03-16 15:20:00

With varying levels of detail, such as omitting time, seconds, etc.

I know that for some applications, you can configure this manually, but I'd like it to be automatically set for every program.

I'm specifically using Ubuntu Intrepid, but a general solution that would work across all distributions would be best.

Answer 1

Set your locale date environment variable LC_TIME to "en_DK" Set it in your .bashrc or similar, or check man locale for how to set it system-wide.

On ArchLinux all of the Locale settings are in /etc/rc.conf and customisations are set up in /etc/rc.local

#!/bin/bash
# Local multi-user startup script
export LC_TIME="en_DK"

Answer 2

It's explained at length in this guide: http://ccollins.wordpress.com/2009/01/06/how-to-change-date-formats-on-ubuntu/

Answer 3

Open locale.conf with your editor

# $EDITOR /etc/locale.conf

and insert the line

TIME_STYLE=iso

after saving the file run

# locale-gen
# env-update && source /etc/profile

and test the result

# ls -al /home
drwxr-xr-x   8 root             root      4096 2011-12-2  .
...

Answer 4

Some people would advise to change your local to german "en_DK" this kind of works if you don't mind the day and month names being in german. Since I cannot post hyperlinks,and this board sees my linux commands as hyperlinks.... (nice one)... I can only say you search (google) how-to-change-date-formats-on-ubuntu and click the first link.

Answer 5

I wish this were generally possible, but POSIX locale categories have only so many formats, most of which correspond to more historic formats/scenarios, but if you get d_fmt and t_fmt right, things seem to improve generally. Some time ago, I’ve created one that comes as suitably close to a full ISO 8601 locale as possible on a Debian GNU/Linux (glibc) system.

The way to do this correctly is not entirely trivial. You’ve got to create a full locale of your own, even if you only use it for LC_CTIME. You’ve got to edit some values manually, but only for date/time; you can, thankfully, just include the defaults for the others.

I’ve done this for de_DE (or rather de_DE.UTF-8) as base locale. The resulting locale definition file looks as follows (but read on below):

comment_char %
escape_char /

% $MirOS: contrib/hosted/tg/deb/de_DE@iso8601,v 1.1 2021/04/05 21:13:47 tg Exp $
%-
% This is an alternative locale definition file, GNU libc compatible,
% which provides an LC_TIME category that is mostly conformant to DIN
% 5008 and ISO 8601. It uses %-d as an extension (use the alternative
% date_fmt if not supported); the timezone offset is rendered without
% colon due to https://bugs.debian.org/799476 which is not proper but
% the best we can currently do; date +'%Y-%m-%dT%H:%M:%S%:z' works.
%
% Install with:
% $ sudo localedef -i de_DE@iso8601 -f UTF-8 -c de_DE.UTF-8@iso8601

% glibc
LC_IDENTIFICATION
title     "German locale for Germany with DIN ISO 8601 date/time format"
source    "BOSng"
contact   "mirabilos"
language  "German"
territory "Germany"
revision  "1.0"
date      "2021-04-04"

category "i18n:2012";LC_IDENTIFICATION
category "i18n:2012";LC_CTYPE
category "i18n:2012";LC_COLLATE
category "i18n:2012";LC_TIME
category "i18n:2012";LC_NUMERIC
category "i18n:2012";LC_MONETARY
category "i18n:2012";LC_MESSAGES
category "i18n:2012";LC_PAPER
category "i18n:2012";LC_NAME
category "i18n:2012";LC_ADDRESS
category "i18n:2012";LC_TELEPHONE
category "i18n:2012";LC_MEASUREMENT
END LC_IDENTIFICATION

% POSIX
LC_CTYPE
copy "de_DE"
END LC_CTYPE

% POSIX
LC_COLLATE
copy "de_DE"
END LC_COLLATE

% POSIX
LC_TIME
abday         "So";"Mo";"Di";"Mi";"Do";"Fr";"Sa"
day           "Sonntag";/
              "Montag";/
              "Dienstag";/
              "Mittwoch";/
              "Donnerstag";/
              "Freitag";/
              "Samstag"
abmon         "Jan.";/
              "Feb.";/
              "M<U00E4>rz";/
              "Apr.";/
              "Mai";/
              "Juni";/
              "Juli";/
              "Aug.";/
              "Sep.";/
              "Okt.";/
              "Nov.";/
              "Dez."
mon           "Januar";/
              "Februar";/
              "M<U00E4>rz";/
              "April";/
              "Mai";/
              "Juni";/
              "Juli";/
              "August";/
              "September";/
              "Oktober";/
              "November";/
              "Dezember"
% this *should* be the first line; GNU cannot even do its own extensions right
%d_t_fmt      "%Y-%m-%dT%H:%M:%S%:z (%Z), %G-W%V-%u (%a)"
d_t_fmt       "%Y-%m-%dT%H:%M:%S%z (%Z), %G-W%V-%u (%a)"
d_fmt         "%Y-%m-%d"
t_fmt         "%H:%M:%S"
am_pm         "";""
t_fmt_ampm    ""
week          7;19971130;4
first_weekday 2
first_workday 2
cal_direction 1
% use the second line if %-d does not work for you
date_fmt      "%A, %-d. %B %Y, %H:%M:%S %Z"
%date_fmt     "%a %Y-%m-%d, %H:%M:%S %Z"
END LC_TIME

% POSIX
LC_NUMERIC
copy "de_DE"
END LC_NUMERIC

% POSIX
LC_MONETARY
copy "de_DE"
END LC_MONETARY

% POSIX
LC_MESSAGES
copy "de_DE"
END LC_MESSAGES

% glibc
LC_PAPER
copy "de_DE"
END LC_PAPER

% glibc
LC_NAME
copy "de_DE"
END LC_NAME

% glibc
LC_ADDRESS
copy "de_DE"
END LC_ADDRESS

% glibc
LC_TELEPHONE
copy "de_DE"
END LC_TELEPHONE

% glibc
LC_MEASUREMENT
copy "de_DE"
END LC_MEASUREMENT

If you wish to do this for some other locale, such as es_ES, you’ll need to make the following modifications to it (in my example, I’m unashamedly copying from glibc localedata/locales/es_ES):

• change title, language and territory in the head (and the others, source, contact, revision and date as well while there) to suitable values (e.g. language Spanish, territory Spain)
• if not using glibc, you might need to remove a few entries commented with % glibc (such as LC_NAME), but don’t if your system does support them (the -c flag to localedef should also make it accept that, but YMMV)
• change all the copy "de_DE" lines (there’s a lot of them!) to copy "es_ES"
• change abday to a list of weekday name abbreviations (starting with Sunday), e.g. "dom";"lun";"mar";"mi<U00E9>";"jue";"vie";"s<U00E1>b" (here you have also the chance to use 2‑letter or 3‑letter abbreviations to suit your taste)
• change day to a list of full weekday names, e.g. "domingo";"lunes";"martes";"mi<U00E9>rcoles";"jueves";"viernes";"s<U00E1>bado"
• change abmon and mon to abbreviated and full month names ("ene";"feb";… and "enero";"febrero";…)
• save as es_ES@iso8601
• change the comment near the beginning appropriately, the compile command is now sudo localedef -i es_ES@iso8601 -f UTF-8 -c es_ES.UTF-8@iso8601

Then, you can export LC_TIME=es_ES.UTF-8@iso8601 to use this. Alternatively, if you do not have superuser priviliegues, you can use LOCPATH (or MUSL_LOCPATH) to install the locale data locally; for glibc, this looks as follows:

mkdir -p ~/.local/locpath
localedef -i es_ES@iso8601 -f UTF-8 -c ~/.local/locpath/es_ES.UTF-8@iso8601

Thereafter, export LOCPATH=$HOME/.local/locpath and LC_TIME=es_ES.UTF-8@iso8601 to use.

For other languages, countries, encodings, etc. proceed correspondingly.

In theory, you can also set LC_ALL to it, since it copies the remaining locale category definitions from the corresponding master file for the chosen locale.

Answer 6

Probably the best way to do this, but not break things is to follow the walkthrough at

http://ccollins.wordpress.com/2009/01/06/how-to-change-date-formats-on-ubuntu/