2013-03-10 09:28:48 +00:00
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.\" %%%LICENSE_START(PUBLIC_DOMAIN)
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2004-11-03 13:51:07 +00:00
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.\" This file is in the public domain, so clarified as of
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.\" 1996-06-05 by Arthur David Olson <arthur_david_olson@nih.gov>.
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2013-03-10 09:28:48 +00:00
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.\" %%%LICENSE_END
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ldd.1, capget.2, clone.2, create_module.2, fallocate.2, futex.2, get_kernel_syms.2, get_thread_area.2, getcpu.2, getitimer.2, getpid.2, io_cancel.2, io_destroy.2, io_getevents.2, io_setup.2, io_submit.2, ioctl_list.2, mkdir.2, mknod.2, pciconfig_read.2, pivot_root.2, posix_fadvise.2, query_module.2, sendfile.2, set_thread_area.2, setns.2, unshare.2, __setfpucw.3, a64l.3, addseverity.3, argz_add.3, bindresvport.3, cabs.3, cacos.3, cacosh.3, canonicalize_file_name.3, carg.3, casin.3, casinh.3, catan.3, catanh.3, ccos.3, ccosh.3, cerf.3, cexp.3, cexp2.3, cimag.3, clog.3, clog10.3, clog2.3, cmsg.3, conj.3, cpow.3, cproj.3, creal.3, csin.3, csinh.3, csqrt.3, ctan.3, ctanh.3, des_crypt.3, envz_add.3, fdim.3, fma.3, fmax.3, fmemopen.3, fmin.3, fmtmsg.3, fpclassify.3, gamma.3, getpt.3, getrpcent.3, getrpcport.3, getttyent.3, isgreater.3, key_setsecret.3, lgamma.3, malloc_hook.3, mempcpy.3, nan.3, netlink.3, nextafter.3, putgrent.3, remove.3, remquo.3, rpc.3, rtime.3, rtnetlink.3, setaliasent.3, setnetgrent.3, signbit.3, significand.3, sincos.3, stdin.3, tgamma.3, xcrypt.3, xdr.3, cciss.4, hpsa.4, mouse.4, pts.4, sk98lin.4, tty_ioctl.4, wavelan.4, hosts.equiv.5, rpc.5, tzfile.5, boot.7, complex.7, ddp.7, fifo.7, futex.7, icmp.7, ip.7, ipv6.7, netdevice.7, netlink.7, packet.7, raw.7, rtnetlink.7, socket.7, tcp.7, udp.7, unix.7, x25.7, sync.8: Global fix: Put copyright info at top of page, followed by blank line and LICENSE
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2013-03-10 09:29:51 +00:00
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.\"
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.\" @(#)tzfile.5 7.11
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.\"
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add_key.2, chown.2, epoll_ctl.2, epoll_wait.2, execve.2, fcntl.2, get_mempolicy.2, getxattr.2, ioctl.2, keyctl.2, listxattr.2, mkdir.2, mknod.2, mmap.2, msync.2, nfsservctl.2, open.2, prctl.2, removexattr.2, request_key.2, sendfile.2, set_mempolicy.2, setxattr.2, shmget.2, shutdown.2, sigaction.2, syslog.2, truncate.2, umask.2, CPU_SET.3, atexit.3, bsearch.3, cmsg.3, err.3, gethostid.3, getmntent.3, getopt.3, iconv_close.3, inet_ntop.3, longjmp.3, lsearch.3, mcheck.3, on_exit.3, putpwent.3, regex.3, resolver.3, setbuf.3, setjmp.3, setlocale.3, setlogmask.3, sleep.3, strsignal.3, sysconf.3, undocumented.3, tty_ioctl.4, proc.5, resolv.conf.5, tzfile.5, aio.7, bootparam.7, capabilities.7, fanotify.7, inotify.7, ip.7, packet.7, pthreads.7, raw.7, signal.7, socket.7, unix.7, ld.so.8, nscd.8: tstamp
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-05-07 06:26:32 +00:00
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.TH TZFILE 5 2015-05-07 "" "Linux Programmer's Manual"
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2004-11-03 13:51:07 +00:00
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.SH NAME
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2008-09-07 04:17:25 +00:00
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tzfile \- timezone information
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2004-11-03 13:51:07 +00:00
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.SH DESCRIPTION
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2012-05-03 18:52:26 +00:00
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This page describes the structure of the timezone files used by
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.BR tzset (3).
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These files are typically found under one of the directories
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.IR /usr/lib/zoneinfo
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or
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.IR /usr/share/zoneinfo .
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2015-05-02 07:59:01 +00:00
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Timezone information files begin with a 44-byte header structured as follows:
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.IP * 3
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The magic four-byte sequence
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"TZif" identifying this as a
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timezone information file.
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.IP *
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A single character identifying the version of the file's format:
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either an ASCII NUL (\(aq\\0\(aq) or a \(aq2\(aq (\fB0x32\fP).
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.IP *
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Fifteen bytes containing zeros reserved for future use.
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.IP *
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Six four-byte values of type
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2005-11-02 13:55:25 +00:00
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.IR long ,
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2007-12-16 14:08:46 +00:00
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written in a "standard" byte order
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2004-11-03 13:51:07 +00:00
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(the high-order byte of the value is written first).
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These values are,
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in order:
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2015-05-02 07:59:01 +00:00
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.RS
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2004-11-03 13:51:07 +00:00
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.TP
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.I tzh_ttisgmtcnt
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The number of UTC/local indicators stored in the file.
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.TP
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.I tzh_ttisstdcnt
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The number of standard/wall indicators stored in the file.
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.TP
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.I tzh_leapcnt
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The number of leap seconds for which data is stored in the file.
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.TP
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.I tzh_timecnt
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The number of "transition times" for which data is stored
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in the file.
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.TP
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.I tzh_typecnt
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The number of "local time types" for which data is stored
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in the file (must not be zero).
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.TP
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.I tzh_charcnt
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2008-09-07 04:17:25 +00:00
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The number of characters of "timezone abbreviation strings"
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2004-11-03 13:51:07 +00:00
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stored in the file.
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2015-05-02 07:59:01 +00:00
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.RE
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2004-11-03 13:51:07 +00:00
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.PP
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The above header is followed by
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.I tzh_timecnt
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four-byte values of type
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2006-02-09 20:24:53 +00:00
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.IR long ,
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2004-11-03 13:51:07 +00:00
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sorted in ascending order.
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2007-12-16 14:08:46 +00:00
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These values are written in "standard" byte order.
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2004-11-03 13:51:07 +00:00
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Each is used as a transition time (as returned by
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.BR time (2))
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at which the rules for computing local time change.
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Next come
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.I tzh_timecnt
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one-byte values of type
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2006-02-09 20:24:53 +00:00
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.IR "unsigned char" ;
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2007-12-16 14:08:46 +00:00
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each one tells which of the different types of "local time" types
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2004-11-03 13:51:07 +00:00
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described in the file is associated with the same-indexed transition time.
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These values serve as indices into an array of
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.I ttinfo
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2010-08-31 05:49:34 +00:00
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structures (with
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.I tzh_typecnt
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entries) that appear next in the file;
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2004-11-03 13:51:07 +00:00
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these structures are defined as follows:
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2007-12-19 05:53:30 +00:00
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.in +4n
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2004-11-03 13:51:07 +00:00
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.sp
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.nf
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struct ttinfo {
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2007-04-05 13:29:41 +00:00
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long tt_gmtoff;
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int tt_isdst;
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unsigned int tt_abbrind;
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2004-11-03 13:51:07 +00:00
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};
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2007-12-19 05:53:30 +00:00
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.in
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2004-11-03 13:51:07 +00:00
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.fi
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.sp
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Each structure is written as a four-byte value for
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.I tt_gmtoff
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of type
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2006-02-09 20:24:53 +00:00
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.IR long ,
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2004-11-03 13:51:07 +00:00
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in a standard byte order, followed by a one-byte value for
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.I tt_isdst
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and a one-byte value for
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.IR tt_abbrind .
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In each structure,
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.I tt_gmtoff
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gives the number of seconds to be added to UTC,
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.I tt_isdst
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tells whether
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.I tm_isdst
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should be set by
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.BR localtime (3),
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and
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.I tt_abbrind
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2008-09-07 04:17:25 +00:00
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serves as an index into the array of timezone abbreviation characters
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2004-11-03 13:51:07 +00:00
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that follow the
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.I ttinfo
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structure(s) in the file.
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.PP
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Then there are
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.I tzh_leapcnt
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pairs of four-byte values, written in standard byte order;
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the first value of each pair gives the time
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(as returned by
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.BR time (2))
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at which a leap second occurs;
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the second gives the
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.I total
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number of leap seconds to be applied after the given time.
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The pairs of values are sorted in ascending order by time.
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.PP
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Then there are
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.I tzh_ttisstdcnt
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standard/wall indicators, each stored as a one-byte value;
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they tell whether the transition times associated with local time types
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were specified as standard time or wall clock time,
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2008-09-07 04:17:25 +00:00
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and are used when a timezone file is used in handling POSIX-style
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timezone environment variables.
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2004-11-03 13:51:07 +00:00
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.PP
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Finally, there are
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.I tzh_ttisgmtcnt
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UTC/local indicators, each stored as a one-byte value;
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they tell whether the transition times associated with local time types
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were specified as UTC or local time,
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2008-09-07 04:17:25 +00:00
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and are used when a timezone file is used in handling POSIX-style
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timezone environment variables.
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2004-11-03 13:51:07 +00:00
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.PP
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2010-08-31 05:49:34 +00:00
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.BR localtime (3)
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2004-11-03 13:51:07 +00:00
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uses the first standard-time
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.I ttinfo
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structure in the file
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(or simply the first
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.I ttinfo
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structure in the absence of a standard-time structure)
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if either
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.I tzh_timecnt
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is zero or the time argument is less than the first transition time recorded
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in the file.
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2015-05-02 07:54:33 +00:00
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.SS Version 2 format
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2010-08-31 05:49:34 +00:00
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For version-2-format timezone files,
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the above header and data is followed by a second header and data,
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identical in format except that
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2015-05-02 07:54:33 +00:00
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eight bytes are used for each transition time or leap-second time
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(and that the version byte in the header record is
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\fB0x32\fP rather than \fB0x00\fP).
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2010-08-31 05:49:34 +00:00
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After the second header and data comes a newline-enclosed,
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POSIX-TZ-environment-variable-style string for use in handling instants
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after the last transition time stored in the file
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(with nothing between the newlines if there is no POSIX representation for
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such instants).
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2015-05-02 07:54:33 +00:00
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.PP
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The second section of the timezone file consists of another 44-byte header
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record, identical in structure to the one at the beginning of the file,
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except that it applies to the data that follows,
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which is also identical in structure
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to the first section of the timezone file, with the following differences:
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.IP * 3
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The transition time values, after the header, are eight-byte values.
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.IP *
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In each leap second record, the leap second value is an eight-byte value.
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The accumulated leap second count is still a four-byte value.
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.PP
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In all cases, the eight-byte time values are given in
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the "standard" byte order,
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the high-order byte first.
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.SS POSIX timezone string
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The second eight-byte time value section is followed by an optional
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third section:
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a single ASCII newline character (\(aq\\n\(aq),
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then a text string followed by a second
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newline character.
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The text string is a POSIX timezone string, whose format is described in the
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.BR tzset (3)
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manual page.
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.PP
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The POSIX timezone string defines a rule for computing transition times
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that follow the last transition time explicitly specified in the timezone
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information file.
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.SS Summary of the timezone information file format
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\&
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.sp 2
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.RS
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.nf
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Four-byte value section
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(header version \fB0x00\fP or \fB0x32\fP)
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Header record
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Four-byte transition times
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Transition time index
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\fBttinfo\fP structures
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Timezone abbreviation array
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Leap second records
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Standard/Wall array
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UTC/Local array
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Eight-byte value section
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(only if first header version is \fB0x32\fP,
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the second header's version is also \fB0x32\fP)
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Header record
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Eight-byte transition times
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Transition time index
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\fBttinfo\fP structures
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Timezone abbreviation array
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Leap second records
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Standard/Wall array
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UTC/Local array
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Third section
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(optional, only in \fB0x32\fP version files)
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Newline character
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Timezone string
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Newline character
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.fi
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.RE
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2010-08-31 05:49:34 +00:00
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.SH SEE ALSO
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2012-05-03 18:47:45 +00:00
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.BR ctime (3),
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.BR tzset (3),
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2012-05-03 18:56:57 +00:00
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.BR tzselect (8),
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arch_prctl.2, fcntl.2, flock.2, get_robust_list.2, getpriority.2, ioprio_set.2, migrate_pages.2, mmap.2, mremap.2, msync.2, sched_get_priority_max.2, sched_rr_get_interval.2, sched_setparam.2, sched_setscheduler.2, sched_yield.2, select.2, socket.2, subpage_prot.2, unshare.2, btree.3, dbopen.3, dl_iterate_phdr.3, dlopen.3, getnameinfo.3, hash.3, lockf.3, netlink.3, recno.3, rpc.3, xdr.3, cciss.4, console_ioctl.4, hpsa.4, initrd.4, msr.4, rtc.4, st.4, hosts.5, services.5, tzfile.5, aio.7, arp.7, capabilities.7, cpuset.7, feature_test_macros.7, futex.7, inotify.7, ip.7, ipv6.7, iso_8859-16.7, iso_8859-2.7, koi8-r.7, math_error.7, netlink.7, packet.7, pthreads.7, raw.7, spufs.7, udplite.7, uri.7, x25.7: Global fix: Various consistency fixes for SEE ALSO
Coauthored-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2012-09-24 07:53:22 +00:00
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2012-05-03 18:56:57 +00:00
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.I timezone/tzfile.h
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arch_prctl.2, fcntl.2, flock.2, get_robust_list.2, getpriority.2, ioprio_set.2, migrate_pages.2, mmap.2, mremap.2, msync.2, sched_get_priority_max.2, sched_rr_get_interval.2, sched_setparam.2, sched_setscheduler.2, sched_yield.2, select.2, socket.2, subpage_prot.2, unshare.2, btree.3, dbopen.3, dl_iterate_phdr.3, dlopen.3, getnameinfo.3, hash.3, lockf.3, netlink.3, recno.3, rpc.3, xdr.3, cciss.4, console_ioctl.4, hpsa.4, initrd.4, msr.4, rtc.4, st.4, hosts.5, services.5, tzfile.5, aio.7, arp.7, capabilities.7, cpuset.7, feature_test_macros.7, futex.7, inotify.7, ip.7, ipv6.7, iso_8859-16.7, iso_8859-2.7, koi8-r.7, math_error.7, netlink.7, packet.7, pthreads.7, raw.7, spufs.7, udplite.7, uri.7, x25.7: Global fix: Various consistency fixes for SEE ALSO
Coauthored-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2012-09-24 07:53:22 +00:00
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in the glibc source tree
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