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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2012-05-03 18:47:45 +00:00
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.TH TZFILE 5 2012-05-04 "" "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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Timezone information files
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begin with the magic characters "TZif" to identify them as
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2008-09-07 04:17:25 +00:00
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timezone information files,
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2010-08-31 05:49:34 +00:00
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followed by a character identifying the version of the file's format
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2011-09-28 02:52:42 +00:00
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(as of 2005, either an ASCII NUL (\(aq\\0\(aq) or a \(aq2\(aq)
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2011-09-23 01:51:30 +00:00
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followed by fifteen bytes containing zeros reserved for future use,
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followed by 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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(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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.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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stored in the file.
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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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.IR long ,
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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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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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.IR "unsigned char" ;
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each one tells which of the different types of "local time" types
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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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structures (with
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.I tzh_typecnt
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entries) that appear next in the file;
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these structures are defined as follows:
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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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};
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.in
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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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.IR long ,
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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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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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.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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2010-08-31 05:49:34 +00:00
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.PP
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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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eight bytes are used for each transition time or leap-second time.
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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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.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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