CODEWITHSUNDEEP
unixcommand-lineutcautoconf
vy32
vy32

Reputation: 29687

Can I get UTC offset from Unix command line?

I'm writing an autoconf script that needs the current UTC offset. There's no obvious way to get this out of the date program. Is there any straightforward way to get this from a command-line utility, or should I write a test that gets the information and somehow captures it?

Upvotes: 20

Views: 14424

Answers (3)

sage
sage

Reputation: 5514

For others doing ISO8601, you might pick some variant of:

date +%Y%m%dT%H%M%S%z     # 20140809T092143-0700
date -u +%Y%m%dT%H%M%S%z  # 20140809T162143+0000
date -u +%Y%m%dT%H%M%SZ   # 20140809T162143Z

I like those because the lack of punctuation supports universal use. Note that the capital Z is 'hard-coded' for UTC - using %Z will put UTC or the other named timezone. If you prefer punctuation:

date +%Y-%m-%dT%H:%M:%S%z      # 2014-08-09T09:21:43-0700
date +%Y-%m-%dT%H:%M:%S%:z     # 2014-08-09T09:21:43-07:00 - NOT ALL SYSTEMS
date -u +%Y-%m-%dT%H:%M:%S%z   # 2014-08-09T16:21:43+0000
date -u +%Y-%m-%dT%H:%M:%S%:z  # 2014-08-09T16:21:43+00:00 - NOT ALL SYSTEMS
date -u +%Y-%m-%dT%H:%M:%SZ    # 2014-08-09T16:21:43Z

Consult man strftime as supported formats vary. For instance, some systems support inserting colons into the offset using %:z, %::z, or %:::z - only two of my five systems do (Debian, Ubuntu do, but Mac, BusyBox, QNX do not).

And I often go back to https://en.wikipedia.org/wiki/ISO_8601 for reference.

Upvotes: 7

Till
Till

Reputation: 3154

Try this, and see whether it works for you:

date +%z

Upvotes: 34

Lightness Races in Orbit
Lightness Races in Orbit

Reputation: 385325

Yes, date can do this:

[tomalak@lolphin:~] date -R
Mon, 02 May 2011 17:37:45 +0100

Or, more specifically:

[tomalak@lolphin:~] date -R | awk '{print $6}'
+0100
[tomalak@lolphin:~] date +%z
+0100

Reading date --help is very useful.

Upvotes: 4

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