timezone
- timezone setup
- tzdata installation with noninteractive
date
- epoch
- timestamps
- format
- IOS 8601
- rfc-3339
- utc
- timezone
- common formats
convert

references:

* imarslo: groovy time

https://en.wikipedia.org/wiki/Unix_time:

timezone

timezone setup

$ sudo dpkg-reconfigure tzdata

tzdata installation with noninteractive

[!NOTE|label:references:]

apt-get install tzdata noninteractive

# in bash
$ DEBIAN_FRONTEND=noninteractive sudo apt-get install -y tzdata

# or
$ export DEBIAN_FRONTEND=noninteractive
$ sudo apt install -y tzdata

# or
$ echo 'tzdata tzdata/Areas select Europe'       | debconf-set-selections
$ echo 'tzdata tzdata/Zones/Europe select Paris' | debconf-set-selections
$ DEBIAN_FRONTEND="noninteractive" sudo apt install -y tzdata

# or
$ sudo ln -fs /usr/share/zoneinfo/America/New_York /etc/localtime
$ export DEBIAN_FRONTEND=noninteractive
$ sudo apt-get install -y tzdata
$ sudo dpkg-reconfigure --frontend noninteractive tzdata

[!NOTE|label:references:]

Cingulata/Dockerfile.bfv

$ sudo ln -snf /usr/share/zoneinfo/$(curl https://ipapi.co/timezone) /etc/localtime
$ sudo apt install -y tzdata

or in dockerfile

RUN apt-get update \
    && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends tzdata

or ENV in dockerfile

[!NOTE|label:references:]

setting it via ENV should be actively discouraged

ENV DEBIAN_FRONTEND noninteractive
RUN apt-get update \
    && apt-get install -y --no-install-recommends tzdata

or ARG in dockerfile

[!NOTE|label:references:]

apt-get install tzdata noninteractive

from ubuntu:bionic
ARG DEBIAN_FRONTEND=noninteractive
RUN apt-get update && apt-get install -y tzdata
RUN unlink /etc/localtime
RUN ln -s /usr/share/zoneinfo/America/New_York /etc/localtime

date

epoch

references:

It is the number of seconds that have elapsed since the Unix epoch, minus leap seconds; the Unix epoch is 00:00:00 UTC on 1 January 1970

What is epoch time?

$ date -u -d '1970-01-01 00:00:00' '+Normal: %F %T %:z%nUnix: %s'
Normal: 1970-01-01 00:00:00 +00:00
Unix: 0

$ date -d '1970-01-01 00:00:00' '+Normal: %F %T %:z%nUnix: %s'
Normal: 1970-01-01 00:00:00 +08:00
Unix: -28800

$ date -u -d '1970-01-01 00:00:00 UTC +1 day' '+Normal: %F %T %:z%nUnix: %s'
Normal: 1970-01-02 00:00:00 +00:00
Unix: 86400

$ date -d '2023-01-01' +%s; date -d '2023-01-01 - 1 year' +%s
1672560000
1641024000

# using now
$ date -d'now' +%s; date -d 'now - 1 day' +%s
1706952065
1706865665

$ date '+%s%3N'
1602231334983

$ date '+%s'
1602231334

timestamps

format

[!TIP]

yyyy-MM-dd'T'HH:mm:ss.SSSZ

yyyy-MM-dd'T'HH:mm:ss

DATE FORMAT OPTION	MEANING	EXAMPLE OUTPUT
`date +%c`	locale’s date time	Sat May 9 11:49:47 2020
`date +%x`	locale’s date	05/09/20
`date +%X`	locale’s time	11:49:47
`date +%A`	locale’s full weekday name	Saturday
`date +%B`	locale’s full month name	May
`date +%m-%d-%Y`	MM-DD-YYYY date format	05-09-2020
`date +%D`	MM/DD/YY date format	05/09/20
`date +%F`	YYYY-MM-DD date format	2020-05-09
`date +%T`	HH:MM:SS time format	11:44:15
`date +%u`	Day of Week	6
`date +%U`	Week of Year with Sunday as first day of week	18
`date +%V`	ISO Week of Year with Monday as first day of week	19
`date +%j`	Day of Year	130
`date +%Z`	Timezone	PDT
`date +%m`	Month of year (MM)	05
`date +%d`	Day of Month (DD)	09
`date +%Y`	Year (YY)	2020
`date +%H`	Hour (HH)	11
`date +%H`	Hour (HH) in 24-hour clock format	11
`date +%I`	Hour in 12-hour clock format	11
`date +%p`	locale’s equivalent of AM or PM	AM
`date +%P`	same as %p but in lower case	am

classical date format

$ secs=259200

$ date -u -d @${secs} +"%F"
1970-01-04
$ date -u -d @${secs} +"%T"
00:00:00

$ date -u -d @${secs} +"%F %T"
1970-01-04 00:00:00

$ date -u -d @${secs} -Is
1970-01-04T00:00:00+00:00

date format with timezone

$ date -u +"%Y-%m-%dT%H:%M:%SZ"
2020-10-09T08:14:47Z

$ date +%FT%T.%3N%:z
2020-10-09T17:27:18.491+08:00

$ date -u +"%Y-%m-%dT%H:%M:%S.%3NZ"
2020-10-09T08:14:47.167Z

$ date +%Y-%m-%d-T%H:%M:%S.%3N%z
2020-10-09-T17:27:18.491+0800

details

$ date -u -d "2019-01-19T05:00:00 - 2 hours" +%Y-%m-%d_%H:%M:%S%Z --debug
date: parsed datetime part: (Y-M-D) 2019-01-19 05:00:00 UTC-02
date: parsed relative part: +1 hour(s)
date: input timezone: parsed date/time string (-02)
date: using specified time as starting value: '05:00:00'
date: starting date/time: '(Y-M-D) 2019-01-19 05:00:00 TZ=-02'
date: '(Y-M-D) 2019-01-19 05:00:00 TZ=-02' = 1547881200 epoch-seconds
date: after time adjustment (+1 hours, +0 minutes, +0 seconds, +0 ns),
date:     new time = 1547884800 epoch-seconds
date: timezone: Universal Time
date: final: 1547884800.000000000 (epoch-seconds)
date: final: (Y-M-D) 2019-01-19 08:00:00 (UTC)
date: final: (Y-M-D) 2019-01-19 08:00:00 (UTC+00)
2019-01-19_08:00:00UTC

IOS 8601

FORMAT EXAMPLE

YYYY 2015

YYYY-MM 2015-12

YYYY-MM-DD 2015-12-11

YYYY-MM-DD'T'hh:mmTZD 2015-12-11T20:28+01:00 or 2015-12-11T19:28Z

YYYY-MM-DD'T'hh:mm:ssTZD 2015-12-11T20:28:30+01:00 or 2015-12-11T19:28:30Z

YYYY-MM-DD'T'hh:mm:ss.sTZD 2015-12-11T20:28:30.45+01:00 or 2015-12-11T19:28:30.45Z

where:

YYYY = four-digit year

MM = two-digit month (01=January, etc.)

DD = two-digit day of month (01 through 31)

hh = two digits of hour (00 through 23) (am/pm NOT allowed)

mm = two digits of minute (00 through 59)

ss = two digits of second (00 through 59)

s = one or more digits representing a decimal fraction of a second (i.e. milliseconds)

TZD = time zone designator (Z or +hh:mm or -hh:mm)

FORMAT	EXAMPLE
YYYY	2015
YYYY-MM	2015-12
YYYY-MM-DD	2015-12-11
YYYY-MM-DD'T'hh:mmTZD	2015-12-11T20:28+01:00 or 2015-12-11T19:28Z
YYYY-MM-DD'T'hh:mm:ssTZD	2015-12-11T20:28:30+01:00 or 2015-12-11T19:28:30Z
YYYY-MM-DD'T'hh:mm:ss.sTZD	2015-12-11T20:28:30.45+01:00 or 2015-12-11T19:28:30.45Z

$ date -I
2020-10-09

$ date -Is && date -Isecond
2020-10-09T16:31:47+08:00
2020-10-09T16:31:47+08:00

$ date -Ih
2020-10-09T16+08:00

$ date -Im
2020-10-09T16:31+08:00

rfc-3339

$ date --rfc-3339=date
2020-10-09

$ date --rfc-3339=ns
2020-10-09 17:32:14.158684000+08:00

$ date --rfc-3339=seconds
2020-10-09 17:32:14+08:00

utc

$ date
Fri Oct  9 17:09:34 CST 2020

$ date -u
Fri Oct  9 09:09:34 UTC 2020

timezone

[!NOTE|label:references:]
list all timezone:
$ timedatectl list-timezones | more

# or
$ tree /usr/share/zoneinfo/
tzdb timezone descriptions

$ date '+%Z'
CST

$ date '+%z'
+0800

$ date '+%:z'
+08:00

$ date '+%::z'
+08:00:00

$ date '+%:::z'
+08

$ echo $TZ
Asia/Beijing

$ timedatectl
      Local time: Tue 2023-08-22 05:58:45 CST
  Universal time: Mon 2023-08-21 21:58:45 UTC
        RTC time: Mon 2023-08-21 21:53:46
       Time zone: Asia/Beijing (CST, +0800)
     NTP enabled: yes
NTP synchronized: yes
 RTC in local TZ: no
      DST active: n/a

$ date -d "2024-03-11" +"%Z"
PDT
$ date -d "2024-03-10" +"%Z"
PST

common formats

[!NOTE|label:references:] Shell command: date Most common Bash date commands for timestamping

FORMAT/RESULT	COMMAND	OUTPUT
`YYYY-MM-DD`	`date -I`	2020-10-09
`YYYY-MM-DD_hh:mm:ss`	`date +%F_%T`	2020-10-09_16:48:45
`YYYYMMDD_hhmmss`	`date +%Y%m%d_%H%M%S`	20201009_164845
`YYYYMMDD_hhmmss (UTC version)`	`date --utc +%Y%m%d_%H%M%SZ`	20201009_084845Z
`YYYYMMDD_hhmmss (with local TZ)`	`date +%Y%m%d_%H%M%S%Z`	20201009_164845CST
`YYYYMMSShhmmss`	`date +%Y%m%d%H%M%S`	20201009164845
`YYYYMMSShhmmssnnnnnnnnn`	`date +%Y%m%d%H%M%S%N`	20201009164845495302000
`YYMMDD_hhmmss`	`date +%y%m%d_%H%M%S`	201009_164845
`Seconds since UNIX epoch:`	`date +%s`	1602233325
`Nanoseconds only:`	`date +%N`	505337000
`Nanoseconds since UNIX epoch:`	`date +%s%N`	1602233325508581000
`Nanoseconds since UNIX epoch:`	`date +%s%3N`	1602233325508
`ISO8601 UTC timestamp`	`date --utc +%FT%TZ`	2020-10-09T08:48:45Z
`ISO8601 UTC timestamp`	`date --utc +%FT%T%Z`	2020-10-09T08:48:45UTC
`ISO8601 UTC timestamp + ms`	`date --utc +%FT%T.%3NZ`	2020-10-09T08:48:45.517Z
`ISO8601 UTC timestamp + ms`	`date --utc +%FT%T.%3N%Z`	2020-10-09T08:48:45.520UTC
`ISO8601 Local TZ timestamp`	`date +%FT%T%Z`	2020-10-09T16:48:45CST
`YYYY-MM-DD (Short day)`	`date +%F$%a$`	2020-10-09(Fri)
`YYYY-MM-DD (Long day)`	`date +%F$%A$`	2020-10-09(Friday)

convert

$ date +"%Y-%m-%dT%H:%M:%SZ"
2020-10-09T17:16:37Z

$ date -u +"%Y-%m-%dT%H:%M:%SZ"
2020-10-09T09:16:37Z

$ date -d $(date -u +"%Y-%m-%dT%H:%M:%SZ")
Fri Oct  9 17:16:37 CST 2020

HUMAN-READABLE TIME	SECONDS
1 hour	3600 seconds
1 day	86400 seconds
1 week	604800 seconds
1 month (30.44 days)	2629743 seconds
1 year (365.24 days)	31556926 seconds

timestamps to epoch

$ echo $EPOCHSECONDS
1602235097

$ date -d $(date -u +"%Y-%m-%dT%H:%M:%SZ") +%s
1602235097
$ date --date=$(date -u +"%Y-%m-%dT%H:%M:%S.%3NZ") +%s%3N
1602235097801

$ date -d '2023-01-01' +%s; date -d '2023-01-01 - 1 day' +%s
1672560000
1672473600

$ date -d '2023-01-01' +%s; date -d '2023-01-01 - 1 year' +%s
1672560000
1641024000

# using now
$ date -d'now' +%s; date -d 'now - 1 day' +%s
1706952065
1706865665

epoch to timestamps

$ date -u +"%Y-%m-%dT%H:%M:%S.%3NZ"
2020-10-09T09:18:17.795Z

$ date -d @1602235097 +%c
Fri Oct  9 17:18:17 2020

$ date -d @1602235097
Fri Oct  9 17:18:17 CST 2020

$ date -d @1602235097 -u
Fri Oct  9 09:18:17 UTC 2020

convert epoch with milliseconds

Convert unix timestamp to hh:mm:ss:SSS (where SSS is milliseconds)

d=$(date +%s%3N)
s=${d%???}
ms=${d#"$s"}
date -d "@$s" +"%F %T.$ms %z"

result

2020-10-09 18:28:34.534 +0800

d: 1602239314534
s: 1602239314
ms: 534

convert in different timezone

[!NOTE|label:references:]
CST to UTC conversion
timezone can be found via:
$ cat /usr/share/zoneinfo

# or
$ timedatectl list-timezones | more

$ TZ="Asia/Shanghai" date -d @$(date -d "2023-01-01 00:00:00 GMT" +"%s")
Sun Jan  1 08:00:00 CST 2023

$ TZ="America/Los_Angeles" date -d @$(date -d "2023-01-01 00:00:00 GMT" +"%s")
Sat Dec 31 16:00:00 PST 2022

convert to another timezone

$ date --date='TZ="GTM" 15:00 tomorrow'
Tue Aug 22 08:00:00 PDT 2023

$ echo $TZ
America/Los_Angeles
$ date --date='TZ="Asia/Shanghai" 16:00 tomorrow'
Wed Aug 23 01:00:00 PDT 2023

$ echo $TZ
America/Los_Angeles
$ TZ="Asia/Shanghai" date -d 'TZ="America/Los_Angeles" 0:00 tomorrow'
Tue Aug 22 15:00:00 CST 2023

convert to different timezone with daylight saving

$ getDateTime() { echo "$1 | "$( TZ="$1" date '+%Y-%m-%d-%H-%M-%S %Z %z' ); }

$ getDateTime Asia/Hong_Kong
Asia/Hong_Kong | 2024-03-01-13-08-02 HKT +0800

$ getDateTime America/Los_Angeles
America/Los_Angeles | 2024-02-29-21-08-08 PST -0800

$ getDateTime America/New_York
America/New_York | 2024-03-01-00-08-08 EST -0500

$ getDateTime Pacific/Honolulu
Pacific/Honolulu | 2024-02-29-19-08-08 HST -1000

$ getDateTime Asia/Hong_Kong
Asia/Hong_Kong | 2024-03-01-13-08-09 HKT +0800

get daylight saving

$ date -d "2024-03-11" +%Z
PDT
$ date -d "2024-03-10" +%Z
PST

$ echo $(( ($(date -d "2024-03-10 UTC" +%s) - $(date -d "2024-03-10 PST" +%s))/(60*60) ))
-8
$ echo $(( ($(date -d "2024-03-11 UTC" +%s) - $(date -d "2024-03-11 PDT" +%s))/(60*60) ))
-7

another

$ if perl -e 'exit ((localtime)[8])' ; then
    echo winter
  else
    echo summer
  fi

how many days from timestamps

[!NOTE|label:references:]

How to find the difference in days between two dates?

$ echo $(( ($(date --date="230301" +%s) - $(date --date="240301" +%s) )/(60*60*24) )) days
-366 days

# with timezone
#                PST/PDT according to daylight saving
#                                  v
$ echo $(( ($(date -d "2024-03-01 PST" +%s) - $(date -d "2023-03-01 UTC" +%s)) / (60*60*24) ))
366

calculate time different

$ date -d 'now + 3 weeks'
Fri Oct 30 20:32:04 CST 2020

$ date -d 'now + 3 weeks' +%s
1604061130

$ date -d 'Jan 1 + 11 weeks'
Wed Mar 18 00:00:00 CST 2020

$ date -d 'Jan 1 2021 + 11 weeks'
Fri Mar 19 00:00:00 CST 2021

time described by STRING

$ date -u +"%Y-%m-%dT%H:%M:%S.%3NZ" -d '90 day ago'
2020-07-11T08:14:03.145Z

$ date -u +"%Y-%m-%dT%H:%M:%S.%3NZ" -d '3 months ago'
2020-07-09T08:14:47.164Z

$ date -u -d "2019-01-19T05:00:00Z - 2 hours" +%Y-%m-%d_%H:%M:%S
2019-01-19_03:00:00

$ date -d "$(date -Iseconds -d "2018-12-10 00:00:00") - 5 hours - 20 minutes - 5 seconds"
Sun Dec  9 18:39:55 CST 2018

$ date -d "2018-12-10 00:00:00 5 hours ago 20 minutes ago 5 seconds ago"
Sun Dec  9 18:39:55 CST 2018

$ date -d '2023-01-01 - 1 year' +"%Y-%m-%d %H:%M:%S"
2022-01-01 00:00:00

two times different

$ seconds=$(date +%s)
$ printf "%d days %(%H hours %M minutes %S seconds)T\n" $((seconds/86400)) $seconds
18544 days 18 hours 35 minutes 48 seconds

simple one-liner

$ secs=259200
$ printf '%dh:%dm:%ds\n' $(($secs/3600)) $(($secs%3600/60)) $(($secs%60))
72h:0m:0s

with leading zero

$ printf '%02dh:%02dm:%02ds\n' $(($secs/3600)) $(($secs%3600/60)) $(($secs%60))
72h:00m:00s

with days

$ printf '%dd:%dh:%dm:%ds\n' $(($secs/86400)) $(($secs%86400/3600)) $(($secs%3600/60))   $(($secs%60))
3d:0h:0m:0s

with nanoseconds

$ printf '%02dh:%02dm:%02fs\n' $(echo -e "$secs/3600\n$secs%3600/60\n$secs%60"| bc | xargs echo)
72h:00m:0.000000s

`datediff` (`ddiff`)

$ datediff -f "%d days, %H hours, %M mins, %S secs" "$(date +'%Y-%m-%d %H:%M:%S')" "$(date +'%Y-%m-%d %H:%M:%S' -d '3 days ago')"
-3 days, 0 hours, 0 mins, 0 secs

or with specific format

$ ddiff -i '%Y%m%d%H%M%S' 20190817040001 20200312000101
17956860s

$ ddiff -f "%d days, %H hours, %M mins, %S secs" -i '%Y%m%d%H%M%S' 20190817040001 20200312000101
207 days, 20 hours, 1 mins, 0 secs

calculate with epoch

$ awk -v t=$(( $(date -d $(date +"%Y-%m-%dT%H:%M:%SZ") +%s) - $(date -d $(date +"%Y-%m-%dT%H:%M:%SZ" -d '3 days ago') +%s) )) 'BEGIN{
  printf "%d:%02d:%06.3f\n", t/3600, (t/60)%60, t%60}'
72:00:00.000

transfer date format

[!TIP]

$ date +'%Y%m%d%H%M%S'
20201009184852

$ d1=$(date +'%Y%m%d%H%M%S')
$ date --date "$(echo $d1 | sed -nr 's/(....)(..)(..)(..)(..)(..)/\1-\2-\3 \4:\5:\6/p')"
Fri Oct  9 18:48:52 CST 2020

time & date

timezone

timezone setup

tzdata installation with noninteractive

date

epoch

timestamps

format

IOS 8601

rfc-3339

utc

timezone

common formats

convert

timestamps to epoch

epoch to timestamps

convert in different timezone

get daylight saving

how many days from timestamps

calculate time different

time described by STRING

two times different

simple one-liner

`datediff` (`ddiff`)

calculate with epoch

transfer date format

results matching ""

No results matching ""

timezone

timezone setup

tzdata installation with noninteractive

date

epoch

timestamps

format

IOS 8601

rfc-3339

utc

timezone

common formats

convert

timestamps to epoch

epoch to timestamps

convert in different timezone

get daylight saving

how many days from timestamps

calculate time different

time described by STRING

two times different

simple one-liner

datediff (ddiff)

calculate with epoch

transfer date format

results matching ""

No results matching ""

`datediff` (`ddiff`)