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Clocks for time travelers

By Colin Beckingham on October 09, 2008 (7:00:00 PM)

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Whether you believe that punctuality is "the politeness of kings" or "the art of guessing how late the other fellow is going to be," you can count on your Linux box for information about local times across the globe, so that you can plan a punctual VoIP call, stock transaction, or meeting. Here are some world clocks that work well on the desktop.

World time is a topic fraught with complexities and exceptions: Daylight Savings Time, fractional hour discrepancies, exceptional time zones, today, tomorrow, or yesterday. Some tools handle these difficulties well, and others not so well. On a practical level, however, what you need to know comes down to two basic questions: What time is it right now in Rubovia? And is it a good time to call Mary?

By the way, it almost goes without saying that none of these tools works well if your system clock is inaccurate. You can keep it synced with a network time protocol server by running a command like ntpdate frequently.

General tools

Perhaps the simplest way to learn what time it is elsewhere in the world is to change the locale setting of your desktop. On my KDE 4 desktop under openSUSE 11, for instance, I can right-click the clock and select digital (or analog) clock settings -> Appearance -> Show timezone, then deselect Timezones -> Use local timezone. This activates the list of available timezones, from which I can select the needed timezone and click Apply and OK. The clock then shows the local time in the destination location. You can have multiple clocks, either digital or analog, so this is a quick way to show multiple world times. The big advantage of this approach is that it handles fractional hour differences well, but the system clock lacks any expanded functionality such as alarms or customizable text overlays.

KWorldClock is a part of the KDE installation that also works in GNOME. It displays a graphical representation of the parts of the globe that currently have night or day conditions, and mouse rollovers on the map pop up local time information.

Extendable world clocks

I prefer to have more customizable clocks, responding to situations such as an appointment to call a colleague in Rubovia at 10:00 a.m. Rubovia time. For that to happen I need to mark the clock "Fred-Rubovia" and then set an alarm reminder. A good alternative in this situation is to use a screenlet. Screenlets offer a daemon platform on top of which small Python-based applications operate. A link to the screenlets manager sits in a task panel, and from this common point you can launch or stop various screenlets as required. I installed the basic screenlets package from the 1-Click install at the openSUSE screenlets page; it's also available for other distros.

There are a number of screenlet clocks, including Clock, Digiclock, Kclock, and WallpaperClock, all of which come with the basic install of the manager and have basic functionality. You can also find more customizable clocks, such as WorldClock and Perfect Clock for Linux.

WorldClock is a puzzle for me. I can get it to install, and it while it correctly displays the clock face, it does not display the time on the face. On a different machine or distribution you may have better luck. Even without the display, the alarm works well.

I had better luck with Perfect Clock, as you can see from this example layout. I arranged these four clocks in a square for the purposes of demonstration only; on my desktop I would display them all in a line at the top of my screen, and all would be analog yellow-faced clocks on a blue background, unless I needed to distinguish one for a special purpose. The overlaid notations are MX for Mexico, AR BR for Argentina and Brazil, which share the same time zone, UK for United Kingdom, and OZ for Australia. I set each of the clocks by referring to the time displayed for that region from the basic digital KDE widget.

It took me a while to get the customized text overlay to appear in the clock face of Perfect Clock for Linux. At first I could see nothing, then I found that in a circular clock the default text may be too small and too far into the top left corner to be visible. With a size of 40% for the overall clock, Properties -> Options -> Face gives access to the custom text parameters. I chose a font size of 28 from an installed font such as Sans, clicked the 'text-color' box to select a color (black) and opacity (255). Using the up and down spinners for X and Y position of the text adjusts the text on the face in near real time.

On my machine the alarm on Perfect Clock for Linux screenlets does not work, so it's back to WorldClock for that functionality. Selecting the WorldClock first, sizing the square face to be slightly larger than the Perfect Clock, and editing its functional alarm properties provides the alarm base. Conveniently, the WorldClock alarm can be set in terms of the local or remote timezone. Then I drop the relevant circular clock face of Perfect Clock over WorldClock, leaving the corners of the WorldClock visible beneath. When the WorldClock alarm triggers, the corners surrounding the Perfect Clock flash, giving a visual signal.

A downside of both WorldClock and Perfect Clock for Linux is that neither supports fractional hour differences. In a Canadian context this is significant for my contacts in Newfoundland, which is -1.5 hours relative to my own Toronto time. For the residents of Newfoundland, most other timezones are a non-integer setting distant.

Despite these difficulties, world clocks on the desktop can be useful tools, enabling the Linux user to be strictly prompt, enthusiastically early, or fashionably late according to need or inclination.

Colin Beckingham is a freelance programmer and writer in Eastern Ontario. He is currently working on a project that logs and charts the operation of a biomass burner using open source resources.

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on Clocks for time travelers

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Clocks for time travelers

Posted by: Anonymous [ip:] on October 10, 2008 05:55 PM
Is this article title trying to say that Dr Who would use one of these programs on the Tardis? Just what is a 'time traveler'?


Re: Clocks for time travelers

Posted by: Colin Beckingham on October 10, 2008 08:10 PM
The current title was not the one I proposed to the editorial staff, but I did support the new one for the following reasons:
The origins of the word 'travel' lie in the difficulty of moving one's corporeal existence from one place to another ( When the creative cloud passed by the earth on its way from star xd9985085 in the late 1890s it not only inspired Einstein and the Theory of Relativity but also H.G. Wells in his novel "The Time Machine." The concept of traveling in time-distance was born since we became aware that time was in fact distance and vice versa, putting miles, km and minutes on the same continuum.
I had also used the word 'distant' in relation to the situation of Newfoundland, in the sense of distant meaning two things standing apart: in this case both geographically and in time according to time zone.

Now you could argue that Toronto and Newfoundland are not distant in time since we can both measure our time distance relative to another time point not fixed on earth. But that does not take into account the difference in time of day (relative to noon local time) which imposes a new distance in terms of mental attitude at the time of day. If I call into a different time zone I need to make the effort to place myself mentally in the time of day at the far end, in order to make it appear to the other person that I am actually in that far place.
The word travel also puts me in mind of the French use of the word as in "le bois travaille," that is in changing humidity wooden boards used in construction can warp and creak of their own accord. And when I call into a different time zone it will be to a place that has a slightly different warping of the space time continuum, which of course is detectable.
Ideally a world clock would not only show me the time in the remote location, but the weather, the state of mind of the person at the other end, time of season relative to the grape harvest, and anything else to help ease the travail of effective communications. I see "making the effort to go the extra mile-hour" as a characteristic of the Open Source community.


Clocks for time travelers

Posted by: Anonymous [ip:] on October 13, 2008 08:39 AM
seems to be a lot of work to configure several clocks individually to get to see different timezones.
are there no clocks designed for this purpose like wmtz? it can show 5 timezones, each configured individually. unfortunately it is designed for WindowMaker/Afterstep and does not fit well with other desktop environments.

also, following the WorldClock link the description claims to cover fractional hour differences.

greetings, eMBee.


Re: Clocks for time travelers

Posted by: Colin Beckingham on October 13, 2008 10:02 AM
Whether it is a lot of work or not depends on how much configurability you are looking for.

It is true that the settings for World Clock appear to offer a time based on system time zones. I'd be quite willing to confirm that the World Clock behaves correctly if I could get the time to display in the clock face.


Clocks for time travelers

Posted by: Anonymous [ip:] on October 14, 2008 07:34 PM
I take an article more seriously when the author actually knows the proper terms for things. It's called "Daylight Saving Time". No s.


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