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tztab(4) [hpux man page]

tztab(4)						     Kernel Interfaces Manual							  tztab(4)

tztab - time zone adjustment table for date and ctime() DESCRIPTION
The file describes the differences between Coordinated Universal Time (UTC) and local time. Several local areas can be represented simul- taneously with historical detail. The file consists of one or more time zone adjustment entries. The first line of the entry contains a unique string that may match the value of the string in the user's environment. The format is where is the time zone name or abbreviation, diff is the difference in hours from UTC, and is the name or abbreviation of the "Daylight Savings" time zone. Fractional values of diff are expressed in minutes preceded by a colon. Each such string will start with an alphabetic character. The second and subsequent lines of each entry details the time zone adjustments for that time zone. The lines contain seven fields each. The first six fields specify the first minute in which the time zone adjustment, specified in the seventh field, applies. The fields are separated by spaces or tabs. The first six are integer patterns that specify the minute (0-59), hour (0-23), day of the month (1-31), month of the year (1-12), year (1970-2038), and day of the week (0-6, with 0=Sunday). The minute, hour, and month of the year must contain a number in the (respective) range indicated above. The day of the month, year, and day of the week can contain a number as above or two numbers separated by a minus (indicating an inclusive range). Either the day of the month or the day of the week field must be a range, the other must be simple number. The seventh field is a string that describes the time zone adjustment in its simplest form: where is an alphabetic string giving the time zone name or abbreviation, and diff is the difference in hours from UTC. must match either the field or the field in the first line of the time zone adjustment entry. Any fractional diff is shown in minutes. Comments begin with a in the first column, and include all characters up to a newline. Comments are ignored. EXTERNAL INFLUENCES
International Code Set Support Single-byte character code sets are supported. EXAMPLES
The time zone adjustment table for the Eastern Time Zone in the United States is: Normally (as indicated in the first line) Eastern Standard Time is five hours earlier than UTC. During Daylight Savings time, it changes to a 4 hour difference. The first time Daylight Savings Time took effect (second line) was on January 6, 1974 at 3:00 a.m., EDT. Note that the minute before was 1:59 a.m., EST. The change back to standard time took effect (sixth line) on the last Sunday in November of the same year. At that point, the time went from 1:59 a.m., EDT to 1:00 a.m., EST. The transition to Daylight Savings Time since then has gone from the last Sunday in February (third line) to the last Sunday in April (fourth line) to the first Sunday in April (fifth line). The return to standard time for the same period has remained at the last Sunday in October (seventh line). AUTHOR
was developed by HP. FILES
date(1), ctime(3C), environ(5). tztab(4)

Check Out this Related Man Page

CTIME(2)							System Calls Manual							  CTIME(2)

ctime, localtime, gmtime, asctime, timezone - convert date and time to ASCII SYNOPSIS
#include <u.h> #include <libc.h> char* ctime(long clock) Tm* localtime(long clock) Tm* gmtime(long clock) char* asctime(Tm *tm) /env/timezone DESCRIPTION
Ctime converts a time clock such as returned by time(2) into ASCII (sic) and returns a pointer to a 30-byte string in the following form. All the fields have constant width. Wed Aug 5 01:07:47 EST 1973 Localtime and gmtime return pointers to structures containing the broken-down time. Localtime corrects for the time zone and possible day- light savings time; gmtime converts directly to GMT. Asctime converts a broken-down time to ASCII and returns a pointer to a 30-byte string. typedef struct { int sec; /* seconds (range 0..59) */ int min; /* minutes (0..59) */ int hour; /* hours (0..23) */ int mday; /* day of the month (1..31) */ int mon; /* month of the year (0..11) */ int year; /* year A.D. - 1900 */ int wday; /* day of week (0..6, Sunday = 0) */ int yday; /* day of year (0..365) */ char zone[4]; /* time zone name */ } Tm; When local time is first requested, the program consults the timezone environment variable to determine the time zone and converts accord- ingly. (This variable is set at system boot time by init(8).) The timezone variable contains the normal time zone name and its difference from GMT in seconds followed by an alternate (daylight) time zone name and its difference followed by a newline. The remainder is a list of pairs of times (seconds past the start of 1970, in the first time zone) when the alternate time zone applies. For example: EST -18000 EDT -14400 9943200 25664400 41392800 57718800 ... Greenwich Mean Time is represented by GMT 0 SOURCE
/sys/src/libc/9sys SEE ALSO
date(1), time(2), init(8) BUGS
The return values point to static data whose content is overwritten by each call. Daylight Savings Time is ``normal'' in the Southern hemisphere. These routines are not equipped to handle non-ASCII text, and are provincial anyway. CTIME(2)

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