display or set the system date and time
References
man date
# Display date now
# yyyy-MM-dd HH:mm:ss E ( Java format )
# yyyy-mm-dd HH:ii:ss D ( PHP format )
date +"%Y-%m-%d %H:%M:%S %a"
date +%Y-%m-%d\ %H:%M:%S\ %a
date +%F\ %T\ %a
# 2019-05-03 18:55:25 Fri ( output )
# Display date wanted
date -d "-1 day" # yesterday
# Thu May 2 19:05:08 CST 2019 ( output )
date -d 2018-04-12\ 12:34:56 # specified date
# Thu Apr 12 12:34:56 CST 2018 ( output )
date -d @1601222400 # seconds since Epoch
# Mon Sep 28 00:00:00 CST 2020 ( output )
# Display seconds since Epoch
date +%s -d 2020-09-28\ 00:00:00
# 1601222400 ( output )
# Days between two dates
echo $(( (`date -d 2020-09-28\ 00:00:00 +%s` - `date -d 2020-05-01\ 00:00:00 +%s`) / 86400 )) days
# 150 days ( output )- PHP: date - Manual : https://www.php.net/manual/en/function.date.php
- DateTimeFormatter (Java Platform SE 8 ) : https://docs.oracle.com/javase/8/docs/api/java/time/format/DateTimeFormatter.html
Notice
- Differ
yyyyandYYYYformat : https://stackoverflow.com/questions/15133549/difference-between-yyyy-and-yyyy-in-nsdateformatter
-d, --date=<STRING>Display time described by STRING, not 'now'.-f, --file=<DATE_FILE>Like--dateonce for each line of DATEFILE-R, --rfc-2822Output date and time in RFC 2822 format.- e.g.: Tue, 16 Oct 2018 16:35:45 +0800
-s, --set=<DATE_STRING>Set time described by STRING-u, --utc, --universalPrint or set Coordinated Universal Time (UTC)
FORMAT controls the output.
See below for interpreted sequences.
| Format | Explanation |
|---|---|
| %a | abbreviated weekday name (e.g., Sun) |
| %A | full weekday name (e.g., Sunday) |
| %b | abbreviated month name (e.g., Jan) |
| %B | full month name (e.g., January) |
| %d | day of month (e.g., 01) |
| %D | date; same as %m/%d/%y |
| %F | full date; same as %Y-%m-%d |
| %g | last two digits of year of ISO (see %G) |
| %H | hour (00..23) |
| %m | month (01..12) |
| %M | minute (00..59) |
| %R | 24-hour hour and minute; same as %H:%M |
| %S | second (00..60) |
| %T | time; same as %H:%M:%S |
| %V | ISO week number, with Monday as first day of week (01..53) |
| %W | week number of year, with Monday as first day of week (00..53) |
| %x | locale's date representation (e.g., 12/31/99) |
| %X | locale's time representation (e.g., 23:13:48) |
| %y | last two digits of year (00..99) |
| %Y | year |
| Format | Explanation |
|---|---|
| %% | a literal % |
| %a | abbreviated weekday name (e.g., Sun) |
| %A | full weekday name (e.g., Sunday) |
| %b | abbreviated month name (e.g., Jan) |
| %B | full month name (e.g., January) |
| %c | date and time (e.g., Thu Mar 3 23:05:25 2005) |
| %C | century; like %Y, except omit last two digits (e.g., 20) |
| %d | day of month (e.g., 01) |
| %D | date; same as %m/%d/%y |
| %e | day of month, space padded; same as %_d |
| %F | full date; same as %Y-%m-%d |
| %g | last two digits of year of ISO (see %G) |
| %H | hour (00..23) |
| %I | hour (01..12) |
| %j | day of year (001..366) |
| %k | hour, space padded ( 0..23); same as %_H |
| %l | hour, space padded ( 1..12); same as %_I |
| %m | month (01..12) |
| %M | minute (00..59) |
| %n | a newline |
| %N | nanoseconds (000000000..999999999) |
| %p | locale's equivalent of either AM or PM; blank if not known |
| %P | like %p, but lower case |
| %r | locale's 12-hour clock time (e.g., 11:11:04 PM) |
| %R | 24-hour hour and minute; same as %H:%M |
| %s | seconds since 1970-01-01 00:00:00 UTC |
| %S | second (00..60) |
| %t | a tab |
| %T | time; same as %H:%M:%S |
| %u | day of week (1..7); 1 is Monday |
| %U | week number of year, with Sunday as first day of week (00..53) |
| %V | ISO week number, with Monday as first day of week (01..53) |
| %w | day of week (0..6); 0 is Sunday |
| %W | week number of year, with Monday as first day of week (00..53) |
| %x | locale's date representation (e.g., 12/31/99) |
| %X | locale's |
| %y | last two digits of year (00..99) |
| %Y | year |
| %z | +hhmm numeric time zone (e.g., -0400) |
| %:z | +hh:mm numeric time zone (e.g., -04:00) |
| %::z | +hh:mm:ss numeric time zone (e.g., -04:00:00) |
| %:::z | numeric time zone with : to necessary precision (e.g., -04, +05:30) |
| %Z | alphabetic time zone abbreviation (e.g., EDT) |
Common
$ date
Sat Oct 13 15:36:49 CST 2018
# CST : China Standard Time$ date -R
Sat, 13 Oct 2018 15:37:03 +0800Full Date Time
$ date +"%Y-%m-%d %H:%M:%S"
# or
$ date +%Y-%m-%d\ %H:%M:%S
# or
$ date +%F\ %T
2018-10-16 17:02:56Option -d
$ date -d 2018-12-31\ 12:34:56
Mon Dec 31 12:34:56 CST 2018
$ date -d "1 day ago"
Mon Oct 15 20:28:39 CST 2018
# others
$ date -s 20120523
$ date -s 01:01:01
$ date -s "01:01:01 2012-05-23"
$ date -s "01:01:01 20120523"
$ date -s "2012-05-23 01:01:01"
$ date -s "20120523 01:01:01"
$ date -d "-1 day" # 昨天
$ date -d "+1 day" # 明天
$ date -d "-1 month" # 上月
$ date -d "+1 month" # 下月
$ date -d "-1 year" # 去年
$ date -d "+1 year" # 明年Option -f
$ cat date_str
2018-01-02 01:02:03
2017-03-16 13:14:15
2016-10-25 12:34:56
$ date -f date_str
Tue Jan 2 01:02:03 CST 2018
Thu Mar 16 13:14:15 CST 2017
Tue Oct 25 12:34:56 CST 2016Make directory named after date & time
$ mkdir `date +%Y%m%d_%H%M%S`
# check
$ ls
20181016_173418Compute duration
#!/bin/bash
start=$(date +%s)
nmap man.linuxde.net &> /dev/null
end=$(date +%s)
difference=$(( end - start ))
echo $difference seconds.Environment TZ : Specifies the timezone, unless overridden by command line parameters.
- If neither is specified, the setting from /etc/localtime is used.
# temporary
$ TZ='Asia/Shanghai'; export TZ
# check
$ echo $TZ
Asia/ShanghaiOther ways
# permanent
# ( `\cp` for skipping interactive confirmation )
$ \cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime
# or
$ TZ=Asia/Shanghai
$ ln -fns /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone$ ls /usr/share/zoneinfo/
Africa EET Greenwich Mexico right
America Egypt Hongkong MST ROC
Antarctica Eire HST MST7MDT ROK
Arctic EST Iceland Navajo Singapore
Asia EST5EDT Indian NZ Turkey
Atlantic Etc Iran NZ-CHAT UCT
Australia Europe iso3166.tab Pacific Universal
Brazil GB Israel Poland US
Canada GB-Eire Jamaica Portugal UTC
CET GMT Japan posix WET
Chile GMT0 Kwajalein posixrules W-SU
CST6CDT GMT-0 Libya PRC zone.tab
Cuba GMT+0 MET PST8PDT Zulu
$ ls /usr/share/zoneinfo/Asia
Aden Dili Kuching Shanghai
Almaty Dubai Kuwait Singapore
Amman Dushanbe Macao Srednekolymsk
Anadyr Gaza Macau Taipei
Aqtau Harbin Magadan Tashkent
Aqtobe Hebron Makassar Tbilisi
Ashgabat Ho_Chi_Minh Manila Tehran
Ashkhabad Hong_Kong Muscat Tel_Aviv
Baghdad Hovd Nicosia Thimbu
Bahrain Irkutsk Novokuznetsk Thimphu
Baku Istanbul Novosibirsk Tokyo
Bangkok Jakarta Omsk Ujung_Pandang
Beirut Jayapura Oral Ulaanbaatar
Bishkek Jerusalem Phnom_Penh Ulan_Bator
Brunei Kabul Pontianak Urumqi
Calcutta Kamchatka Pyongyang Ust-Nera
Chita Karachi Qatar Vientiane
Choibalsan Kashgar Qyzylorda Vladivostok
Chongqing Kathmandu Rangoon Yakutsk
Chungking Katmandu Riyadh Yekaterinburg
Colombo Khandyga Saigon Yerevan
Dacca Kolkata Sakhalin
Damascus Krasnoyarsk Samarkand
Dhaka Kuala_Lumpur Seoul$ timedatectl
Local time: Tue 2018-10-16 17:09:17 CST
Universal time: Tue 2018-10-16 09:09:17 UTC
RTC time: Tue 2018-10-16 09:09:17
Timezone: Asia/Shanghai (CST, +0800)
NTP enabled: yes
NTP synchronized: yes
RTC in local TZ: no
DST active: n/a$ tzselect
# interactions e.g.
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.
#? 5
Please select a country.
1) Afghanistan 18) Israel 35) Palestine
2) Armenia 19) Japan 36) Philippines
3) Azerbaijan 20) Jordan 37) Qatar
4) Bahrain 21) Kazakhstan 38) Russia
5) Bangladesh 22) Korea (North) 39) Saudi Arabia
6) Bhutan 23) Korea (South) 40) Singapore
7) Brunei 24) Kuwait 41) Sri Lanka
8) Cambodia 25) Kyrgyzstan 42) Syria
9) China 26) Laos 43) Taiwan
10) Cyprus 27) Lebanon 44) Tajikistan
11) East Timor 28) Macau 45) Thailand
12) Georgia 29) Malaysia 46) Turkmenistan
13) Hong Kong 30) Mongolia 47) United Arab Emirates
14) India 31) Myanmar (Burma) 48) Uzbekistan
15) Indonesia 32) Nepal 49) Vietnam
16) Iran 33) Oman 50) Yemen
17) Iraq 34) Pakistan
#? 9
Please select one of the following time zone regions.
1) Beijing Time
2) Xinjiang Time
#? 1
The following information has been given:
China
Beijing Time
Therefore TZ='Asia/Shanghai' will be used.
Local time is now: Tue Oct 16 17:23:26 CST 2018.
Universal Time is now: Tue Oct 16 09:23:26 UTC 2018.
Is the above information OK?
1) Yes
2) No
#? yes
Please enter 1 for Yes, or 2 for No.
#? 1
You can make this change permanent for yourself by appending the line
TZ='Asia/Shanghai'; export TZ
to the file '.profile' in your home directory; then log out and log in again.
Here is that TZ value again, this time on standard output so that you
can use the /bin/tzselect command in shell scripts:
Asia/Shanghai