1986-02-15 16:30:57 -05:00
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.TH TZFILE 5
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.SH NAME
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tzfile \- time zone information
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.SH SYNOPSIS
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.B
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#include "tzfile.h"
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.SH DESCRIPTION
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The time zone information files used by
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.IR settz (3)
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and
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.IR newlocaltime (3)
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have the format of the
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.I tzinfo
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structure described in the include file
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.B
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"tzfile.h":
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.sp
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.nf
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.in +.5i
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.ta .5i +\w'struct dsinfo 'u
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struct dsinfo {
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long ds_gmtoff;
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char ds_abbr[TZ_ABBR_LEN+1];
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char ds_isdst;
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};
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struct tzinfo {
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int tz_timecnt;
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long tz_times[TZ_MAX_TIMES];
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char tz_types[TZ_MAX_TIMES];
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struct dsinfo tz_dsinfo[TZ_MAX_TYPES];
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};
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.fi
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.PP
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The
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.B tz_timecnt
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field tells how many of the
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.B tz_times
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and
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.B tz_types
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stored in the file are meaningful.
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Each of the meaningful
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.B tz_times
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entries is a starting time (as returned by
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.IR time (2));
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the same-indexed
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.B tz_types
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entry is the index of the
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.B tz_dsinfo
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array element that tells about how "local time" is generated starting at that
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time.
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For a file to be used by
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.IR settz ,
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its
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.B tz_times
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entries must be sorted in ascending order.
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.PP
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In the
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.B tz_dsinfo
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structures,
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.B ds_gmtoff
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gives the number of seconds that should be added to GMT;
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.B ds_abbr
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is the ASCII-NUL-terminated string used as the time zone abbreviation;
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and
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.B
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ds_isdst
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tells whether
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.B
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tm_isdst
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should be set by
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.IR newlocaltime (3).
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.PP
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.I Newlocaltime
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uses the first element of
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.B tz_dsinfo
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if either
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.B tz_timecnt
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is zero or
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.IR newlocaltime 's
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argument is less than
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.BR tz_times[0] .
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.SH SEE ALSO
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settz(3)
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