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tzdiff

Displays Timezone differences with localtime in CLI (shell script)

This command was originally "timediff". Now, it's "tzdiff" because of naming conflict.

Usage
- Options
- Format of "-t start" option
Install
Examples
Change Log

Usage

tzdiff [-0lvHN] [-n count] [-f format] [-t start] timezone [timezone ...] [count] [0]

Tzdiff with no arguments will display list of timezones. Tzdiff with timezone will display the time differences of remote time with local time.

Options

-h: show usage
-0: round down to hour
-l: display full timezone name (region/city), only city in default.
-n count: max hours (default: 10)
-f format: output format (using '+output_fmt' of date(1))
-t start: set the start time instead of current time. (see below)
-v: show version of tzdiff.
-H: became the scripting mode. Fields are explicitly separated by single tab instead of an arbitrary space.
-HH: became the scripting mode without timzone name.
-N: display without local timezone.

Format of "-t start" option

If your system has the GNU date, you can use the flexible format. Otherwise, specify as 'YYYY-mm-ddTHH:MM', 'YYYYmmddTHHMM' or 'YYYYmmddTHHMM' and adding 'Z' at the end makes it UTC.

Install

FreeBSD

If you are pkg user, you can easy to install tzdiff like this.

$ sudo pkg install tzdiff

Of course, it is already in ports. You can easy to play with ports.

pkgsrs (NetBSD, Linux, macOS, etc...)

Tzdiff is registered in pkgsrc. If you use pkgsrc, you can easily install it.

macOS

If you are MacPorts user, you can easy to install tzdiff.

$ sudo port install tzdiff

If you are Homebrew user, you can install tzdiff via

$ brew install tzdiff

Debian / Ubuntu

Tzdiff is registerd in debian package, you can easy to install by apt command.

$ sudo apt update
$ sudo apt install tzdiff

Other Platform

In addition to the above, operation has been confirmed on the following platforms:

OpenBSD
CentOS
Windows Subsystem for Linux

Tzdiff is stand alone shell script. It runs on many UNIX-like operating systems as long as it has a POSIX-compatible shell and the GNU date command.

Examples

In these examples, author's timezone is JST.

$ tzdiff America/Los_Angeles
Los_Angeles
2023-06-13 21:08 PDT   2023-06-14 13:08 JST
2023-06-13 22:08 PDT   2023-06-14 14:08 JST
2023-06-13 23:08 PDT   2023-06-14 15:08 JST
2023-06-14 00:08 PDT   2023-06-14 16:08 JST
2023-06-14 01:08 PDT   2023-06-14 17:08 JST
2023-06-14 02:08 PDT   2023-06-14 18:08 JST
2023-06-14 03:08 PDT   2023-06-14 19:08 JST
2023-06-14 04:08 PDT   2023-06-14 20:08 JST
2023-06-14 05:08 PDT   2023-06-14 21:08 JST
2023-06-14 06:08 PDT   2023-06-14 22:08 JST

Tzdiff supports TIMEZONE's completion. tzdiff looks for timezone information in "/usr/share/zoneinfo". For example,

$ tzdiff Lon                                 # enter RETURN instead of TAB
Arctic/Longyearbyen     Europe/London

$ tzdiff Lond
London
2023-06-14 05:13 BST   2023-06-14 13:13 JST
2023-06-14 06:13 BST   2023-06-14 14:13 JST
2023-06-14 07:13 BST   2023-06-14 15:13 JST
2023-06-14 08:13 BST   2023-06-14 16:13 JST
2023-06-14 09:13 BST   2023-06-14 17:13 JST
2023-06-14 10:13 BST   2023-06-14 18:13 JST
2023-06-14 11:13 BST   2023-06-14 19:13 JST
2023-06-14 12:13 BST   2023-06-14 20:13 JST
2023-06-14 13:13 BST   2023-06-14 21:13 JST
2023-06-14 14:13 BST   2023-06-14 22:13 JST

$ tzdiff New_ 0 5
New_York
2023-06-14 00:00 EDT   2023-06-14 13:00 JST
2023-06-14 01:00 EDT   2023-06-14 14:00 JST
2023-06-14 02:00 EDT   2023-06-14 15:00 JST
2023-06-14 03:00 EDT   2023-06-14 16:00 JST
2023-06-14 04:00 EDT   2023-06-14 17:00 JST

It is easy to check changes from daylight saving time to standard time.

$ tzdiff -N -t 2023-11-05T03:00Z Tok Brus New_ Los
Tokyo                  Brussels               New_York               Los_Angeles
2023-11-05 12:00 JST   2023-11-05 04:00 CET   2023-11-04 23:00 EDT   2023-11-04 20:00 PDT
2023-11-05 13:00 JST   2023-11-05 05:00 CET   2023-11-05 00:00 EDT   2023-11-04 21:00 PDT
2023-11-05 14:00 JST   2023-11-05 06:00 CET   2023-11-05 01:00 EDT   2023-11-04 22:00 PDT
2023-11-05 15:00 JST   2023-11-05 07:00 CET   2023-11-05 01:00 EST   2023-11-04 23:00 PDT
2023-11-05 16:00 JST   2023-11-05 08:00 CET   2023-11-05 02:00 EST   2023-11-05 00:00 PDT
2023-11-05 17:00 JST   2023-11-05 09:00 CET   2023-11-05 03:00 EST   2023-11-05 01:00 PDT
2023-11-05 18:00 JST   2023-11-05 10:00 CET   2023-11-05 04:00 EST   2023-11-05 01:00 PST
2023-11-05 19:00 JST   2023-11-05 11:00 CET   2023-11-05 05:00 EST   2023-11-05 02:00 PST
2023-11-05 20:00 JST   2023-11-05 12:00 CET   2023-11-05 06:00 EST   2023-11-05 03:00 PST
2023-11-05 21:00 JST   2023-11-05 13:00 CET   2023-11-05 07:00 EST   2023-11-05 04:00 PST

Specifying "0" and "24" at the end is convenient when you want to know what time 19:00 is your time in a foreign country. It is quicker to display 24 hours than to think.

$ tzdiff Brus 24 0
Brussels
2023-06-14 06:00 CEST   2023-06-14 13:00 JST
2023-06-14 07:00 CEST   2023-06-14 14:00 JST
2023-06-14 08:00 CEST   2023-06-14 15:00 JST
2023-06-14 09:00 CEST   2023-06-14 16:00 JST
2023-06-14 10:00 CEST   2023-06-14 17:00 JST
2023-06-14 11:00 CEST   2023-06-14 18:00 JST
2023-06-14 12:00 CEST   2023-06-14 19:00 JST
2023-06-14 13:00 CEST   2023-06-14 20:00 JST
2023-06-14 14:00 CEST   2023-06-14 21:00 JST
2023-06-14 15:00 CEST   2023-06-14 22:00 JST
2023-06-14 16:00 CEST   2023-06-14 23:00 JST
2023-06-14 17:00 CEST   2023-06-15 00:00 JST
2023-06-14 18:00 CEST   2023-06-15 01:00 JST
2023-06-14 19:00 CEST   2023-06-15 02:00 JST   <= This line is the result you want.
2023-06-14 20:00 CEST   2023-06-15 03:00 JST
2023-06-14 21:00 CEST   2023-06-15 04:00 JST
2023-06-14 22:00 CEST   2023-06-15 05:00 JST
2023-06-14 23:00 CEST   2023-06-15 06:00 JST
2023-06-15 00:00 CEST   2023-06-15 07:00 JST
2023-06-15 01:00 CEST   2023-06-15 08:00 JST
2023-06-15 02:00 CEST   2023-06-15 09:00 JST
2023-06-15 03:00 CEST   2023-06-15 10:00 JST
2023-06-15 04:00 CEST   2023-06-15 11:00 JST
2023-06-15 05:00 CEST   2023-06-15 12:00 JST

Change Log

2024-04-02 1.2.1 No functional changes, but updates the documentation and some coding style.
2023-07-17 1.2 Name changed to city only. Start time can set in UTC.
2019-03-05 1.1 Scripting mode has been added.
2018-12-20 1.0 Manual of tzdiff(1) has been added.
2018-09-04 0.9 Command name changed from 'timediff' to 'tzdiff'.
2018-08-17 0.8 more useful.
2015-08-29 0.1 Initial release.