Bob Miller wrote, >Time servers all speak UTC (Coordinated Universal Time, nee >Greenwich Mean Time) so they don't care about local variances >in daylight saving rules.
And it's probably worth pointing out that Linux (and UNIX in general) uses UTC for its system clock, so no time zone translation has to be done when you synchronize your Linux box with a time server. On Linux, a program finds out what time it is by calling the time() system call. This returns the number of seconds that have elapsed since midnight (UTC), January 1, 1970. It's up to the program to convert this into something more human-readable, such as a date and time in the local time zone. Fortunately, the standard C library supplies several functions (such as localtime() and ctime()) that perform the necessary conversions. When you update your computer to add support for the new time zone rules, the files that get replaced are the rule tables used by the localtime() function. ><trivia> > >I can't find a reference now, but I recall that in Australia, each >state's legislature passes a bill every year defining the dates >for DST for the following year *in that state*. They apparently don't >do that anymore. Here's a summary from the Bureau of Meteorology. > >http://www.bom.gov.au/climate/averages/tables/dst_times.shtml > ></trivia> For lots of other similar time zone trivia, I recommend reading the source code for the time zone rule files[1]. These files are heavily commented, and often rather entertaining. However, if your sense of Order and Security depends on believing that there are people somewhere who understand how time zones work, then you might want to avoid these files, as they will take away your security blanket. The awful truth they reveal is that time zones are a morass of conflicting information usually driven by politics rather than logic, and nobody anywhere knows what the whole story is. - Neil Parker [1] ftp://elsie.nci.nih.gov/pub/ ...look for a file named "tzdata####X.tar.gz", where "####" is a year, and "X" is some letter. _______________________________________________ EUGLUG mailing list [email protected] http://www.euglug.org/mailman/listinfo/euglug
