From where does the date command in Linux get the timezone information?
I cannot see /etc/localtime file and /usr/share/zoneinfo directory in my system. Still when i execute the date command i get the following output
Thu Dec 9 16:28:18 UTC 2010
Kindly tell me from where does the command get the timezone information?
Thanks,
LinuxPenseur
Don't forget that UTC is how standard Unix systems store the date/time in the real time clock. You have to jump through hoops using funny programs (see the hwclock(8) manpage) if you dual-boot to Windows, which prefers the local time to be stored in the CMOS real time clock.
So the date(1) program is simply showing you the results of "I have no configured time zone":
# date -u
Thu Dec 9 10:40:54 UTC 2010
# TZ=UTC date
Thu Dec 9 10:40:57 UTC 2010
# TZ=PST8PDT date
Thu Dec 9 02:41:02 PST 2010
#
From http://www.wikihow.com/Change-the-Timezone-in-Linux
On mobile phones and other small devices that run Linux, the time zone
is stored differently. It is written in /etc/TZ, in the format that is
described, for instance, in [4] . Edit this file manually or use
echo (for instance, echo GMT0BST > /etc/TZ to set the the timezone of
the United Kingdom).
From http://www.radisys.com/files/support_downloads/03245-02_MPCMM0001_MPCMM0002_CMM_Software_TPS.pdf
The CMM determines the offset to local timezone maintained in file
/etc/cmm/TZ and automatically updates the time.
This should help :
http://www.hypexr.org/linux_date_time_help.php
Related
I get result as follow when I execute a sql which includes now()function in VoltDB
select * from test2;
C1
---------------------------
2019-06-29 07:13:38.050000
But,I get another time when I execute a shell command 'date'
[root#localhost config]# date
Sat Jun 29 03:30:09 EDT 2019
How can I make them same？
VoltDB stores time in the UTC timezone. If you want to change this to EDT or any other timezone, you should be able to do it using a variety of methods and languages.
For example, in java you might use VoltTableRow.getTimestampAsSqlTimestamp(0) to get the value of a timestamp row. You could then use DateFormat to convert this to a particular timezone.
You can read more about the "getTimestampAsSqlTimestamp" method here: https://docs.voltdb.com/javadoc/java-client-api/org/voltdb/VoltTableRow.html
Full Disclosure: I work at VoltDB.
just stumbled upon one funny issue in Node.js & MacOs - basically if you run instance of node with set timezone var in .env file, variable TZ, and you local machine is in different timezone, the Date creation is f**d up in the wort way possible, so that:
Timezone is set correctly
But when you create a new Date, the timezone is not reflected
see this example, (my machine is in CET, timezone Europe/Prague) :
~/
11:13 (CET) $ node
new Date()
2019-02-04T10:30:23.053Z # Europe/Prague
new Date().getTimezoneOffset()
-60 # Europe/Prague
.exit
vs. set timezone in TZ env
✔ ~/
11:30 (CET) $ TZ=America/New_York node
new Date()
2019-02-04T10:31:40.968Z # 10:31! :D
new Date().getTimezoneOffset()
300 # America/New_York!
So it is not possible to create a correct date then, since all JS libs like moment uses in the end Date object.
My take is that you should never ever set TZ var while running Node.js server, do I miss something?
Your examples look correct to me. I suspect that your notion of the way the computer keeps track of, and shows, time is upside-down. Your comments imply that you think TZ is used to derive UTC from the computer's internal clock. That's not how it works.
Internally, your Mac is using UTC time. Your Mac is not "in CET". It is "in UTC with a default TZ setting of CET". TZ controls how a local time is derived from the underlying UTC when a local timestamp or timezone offset is required. If you change TZ then local timestamps will be shown in the new timezone, but the computer's internal timekeeping in UTC is not affected.
Specifically for your example, new Date() gets you a Date object representing the current time. The default string representation of a Date object is the UTC time. In your example you can see that this time, shown as the result of the new Date() call:
2019-02-04T10:30:23.053Z # Europe/Prague
is a UTC time because its timezone is shown as Z, indicating UTC. (One way to remember that meaning is that "Z" is for "Zero offset from UTC". This format is sometimes called "Zulu" time because "Zulu" is the ICAO phonetic alphabet's code word for "Z".) If your comment is claiming that this is a local Europe/Prague timestamp then the comment is incorrect.
The result of the second new Date():
2019-02-04T10:31:40.968Z # 10:31! :D
is also shown in UTC and is about a minute later than the first result. It doesn't matter that TZ for this process is different, because TZ does not affect UTC timestamps.
To see the local time, which is calculated by applying the TZ setting to the UTC time obtained from the computer's clock, use the toLocaleString method on the Date object. If you repeat your test using that method you'll see something like this:
$ env TZ=Europe/Prague node
> now = new Date()
2019-02-04T20:26:40.408Z
> now.toLocaleString()
'Mon Feb 04 2019 21:26:40 GMT+0100 (CET)'
$ env TZ=America/New_York node
> now = new Date()
2019-02-04T20:27:12.438Z
> now.toLocaleString()
'Mon Feb 04 2019 15:27:12 GMT-0500 (EST)'
which looks perfectly reasonable.
BTW, Node, or JavaScript, isn't doing anything unusual here. This is the way it works for everything. For example, the date command:
$ env TZ=Europe/Prague date
Mon Feb 4 21:54:49 CET 2019
$ env TZ=America/New_York date
Mon Feb 4 15:54:51 EST 2019
You can solve your issue with moment-timezone node package. below code may help you to resolve your issue.
const moment = require('moment-timezone')
function convertDate(dateInUTCFormat) {
return new Promise((resolve, reject) => {
var dec = moment(dateInUTCFormat);
var normalDate = dec.tz('Asia/Kolkata').format('YYYY-MM-DD'); // GMT +5:30 (India)
resolve(normalDate);
})
}
Also you need to pass the date format that you get in UTC format for eg 2019-02-04T10:30:23.053Z to convertDate function and pass your timezone as i passed my timezone Asia/Kolkata . May this will help you to find your solution.
Is there a script available that can pull the PROGRESS BACKUP STATUS INFO from the log file?
I did a grep on “BACKUP” and it pulls the correct information, but unfortunately there is no time date stamp associated. we are using progress version 9.1D
The end goal would look like this.
Selection Date Range:
Start Date: 07/6/2018
End Date: 7/7/2018
Output:
Date: Mon July 6 20:00 2018
20:03:28 BACKUP 10: Full Backup Started
20:51:44 BACKUP 10: Full Backup Successfully Completed
Date: Mon July 7 20:00 2018
20:03:28 BACKUP 10: Full Backup Started
20:51:44 BACKUP 10: Full Backup Successfully Completed
No. There is no simple "grep" of the log file from version 9 or earlier that will reveal this information.
Prior to version 10 log file entries only contain the time. Not the date. When the day rolls over an entry is written but there are many situations where that date will not be available even for more complex parsing than a simple grep.
Bonus answer: version 9 is ancient, obsolete and unsupported. You should upgrade.
how to get local date & time in linux terminal while server configured in UTC or different timezone?
here is what I get now but I'd like to see in local timezone. For eg: PST/PDT.
[jenkins#myServer ~]$ date
Thu Jul 28 18:16:48 UTC 2016
I'm not looking to change system time using hwclock or updating /etc/localtime. Just want to change it for a user.
Also, please let me know - how to persist it for future logins.
Use the TZ environment variable to pass the desired timezone to date:
TZ=<timezone> date
You can find the available timezones in the /usr/share/zoneinfo/ directory and subdirectories. For example, /usr/share/zoneinfo/America/New_York defines TZ=America/New_York.
Example:
$ date
Fri Jul 29 06:31:53 BDT 2016
$ TZ='America/New_York' date
Thu Jul 28 20:31:58 EDT 2016
$ TZ='America/Los_Angeles' date
Thu Jul 28 17:31:54 PDT 2016
For a local time, use "date". For UTC time, use "date -u". Note that, if you use "date" in the server's terminal it returns the server local time.
You can show local time by overriding the TZ environment variable for the process which prints the date. POSIX says a lot about the topic, beginning with
This variable shall represent timezone information. The contents of the environment variable named TZ shall be used by the ctime(), ctime_r(), localtime(), localtime_r() strftime(), mktime(), functions, and by various utilities, to override the default timezone.
Conventional 3-character timezone values were some time ago (more or less) standardized to deprecate the 3-character forms, using the combined standard and daylight savings time form. The preferred form used for PDT is PST8PDT.
There's a page on VMware showing the names and mentioning that they are used on Linux; you may notice that very few of those are 3-character form (aside from the generic UTC+offset).
Further reading:
Valid timeZone Values (VMware):
IANA - Time Zone Database
I get a date and time that is in the 'America/Chicago' time zone.
My local time zone is 'Australia/Melbourne'.
I need to convert the date/time that is in the 'America/Chicago' time zone to the local timezone('Australia/Melbourne')
I know how to convert a date/time from the local timezone to a date/time in another timezone:
datep="140501 17:31:22"
dateus=`TZ=America/Chicago date -d #$(date +%s -d "${datep}")`
echo ${dateus}
Thu May 1 02:31:22 CDT 2014
However I do not know how to convert a date/time in the 'America/Chicago' timezone to the local timezone('Australia/Melbourne') in the korn shell.
Please advise with an example.
Regards
Harsha
Go via an ISO 8601 timestamp, which includes the offset:
TZ=Australia/Sydney date -d $(TZ=America/Chicago date --i=ns -d "${datep}")
to get:
Fri May 2 08:31:22 AEST 2014
The intermediate time:
2014-05-01T17:31:22,000000000-0500
is parsed unambiguously and presented however you like in the local timezone.