2a1fb74048
POSIX borrowed the "double leap second" bug from C89. Double leap seconds can never happen. This mistake was present in at least POSIX 1997 and fixed by POSIX 2004. I can't find a copy of 2001 online to determine if the bug was present in that revision. While here, remove duplicate language between -d and -t. A few other minor enhancements and an igor (lint) bugfix. Further reading: 2018 POSIX (documents -d): http://pubs.opengroup.org/onlinepubs/9699919799/utilities/touch.html 2004 POSIX (documents SS from 0-60): http://pubs.opengroup.org/onlinepubs/009695399/utilities/touch.html 1997 POSIX/SUSv2 (historical interest, 0-61): http://pubs.opengroup.org/onlinepubs/007908799/xcu/touch.html More on this subject (start at "Unix system time and the POSIX standard") https://www.ucolick.org/~sla/leapsecs/onlinebib.html And: https://marc.info/?l=openbsd-tech&m=92682843416159&w=2 Reported by: Vishal Sahu <vsahu AT isilon.com> Sponsored by: Dell EMC Isilon
251 lines
6.6 KiB
Groff
251 lines
6.6 KiB
Groff
.\" Copyright (c) 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" the Institute of Electrical and Electronics Engineers, Inc.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)touch.1 8.3 (Berkeley) 4/28/95
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.\" $FreeBSD$
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.\"
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.Dd June 1, 2018
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.Dt TOUCH 1
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.Os
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.Sh NAME
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.Nm touch
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.Nd change file access and modification times
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.Sh SYNOPSIS
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.Nm
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.Op Fl A Ar [-][[hh]mm]SS
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.Op Fl achm
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.Op Fl r Ar file
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.Op Fl t Ar [[CC]YY]MMDDhhmm[.SS]
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.Op Fl d Ar YYYY-MM-DDThh:mm:SS[.frac][tz]
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.Ar
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.Sh DESCRIPTION
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The
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.Nm
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utility sets the modification and access times of files.
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If any file does not exist, it is created with default permissions.
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.Pp
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By default,
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.Nm
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changes both modification and access times.
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The
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.Fl a
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and
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.Fl m
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flags may be used to select the access time or the modification time
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individually.
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Selecting both is equivalent to the default.
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By default, the timestamps are set to the current time.
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The
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.Fl d
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and
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.Fl t
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flags explicitly specify a different time, and the
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.Fl r
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flag specifies to set the times those of the specified file.
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The
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.Fl A
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flag adjusts the values by a specified amount.
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.Pp
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The following options are available:
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.Bl -tag -width Ds
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.It Fl A
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Adjust the access and modification time stamps for the file by the
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specified value.
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This flag is intended for use in modifying files with incorrectly set
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time stamps.
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.Pp
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The argument is of the form
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.Dq [-][[hh]mm]SS
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where each pair of letters represents the following:
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.Pp
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.Bl -tag -width Ds -compact -offset indent
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.It Ar -
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Make the adjustment negative: the new time stamp is set to be before
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the old one.
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.It Ar hh
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The number of hours, from 00 to 99.
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.It Ar mm
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The number of minutes, from 00 to 59.
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.It Ar SS
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The number of seconds, from 00 to 59.
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.El
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.Pp
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The
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.Fl A
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flag implies the
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.Fl c
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flag: if any file specified does not exist, it will be silently ignored.
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.It Fl a
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Change the access time of the file.
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The modification time of the file is not changed unless the
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.Fl m
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flag is also specified.
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.It Fl c
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Do not create the file if it does not exist.
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The
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.Nm
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utility does not treat this as an error.
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No error messages are displayed and the exit value is not affected.
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.It Fl d
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Change the access and modification times to the specified date time instead
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of the current time of day.
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The argument is of the form
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.Dq YYYY-MM-DDThh:mm:SS[.frac][tz]
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where the letters represent the following:
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.Bl -tag -width Ds -compact -offset indent
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.It Ar YYYY
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At least four decimal digits representing the year.
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.It Ar MM , Ar DD , Ar hh , Ar mm , Ar SS
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As with
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.Fl t
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time.
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.It Ar T
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The letter
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.Li T
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or a space is the time designator.
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.It Ar .frac
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An optional fraction, consisting of a period or a comma followed by one or
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more digits.
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The number of significant digits depends on the kernel configuration and the
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filesystem, and may be zero.
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.It Ar tz
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An optional letter
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.Li Z
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indicating the time is in
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.Tn UTC .
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Otherwise, the time is assumed to be in local time.
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Local time is affected by the value of the
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.Ev TZ
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environment variable.
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.El
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.It Fl h
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If the file is a symbolic link, change the times of the link
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itself rather than the file that the link points to.
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Note that
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.Fl h
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implies
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.Fl c
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and thus will not create any new files.
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.It Fl m
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Change the modification time of the file.
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The access time of the file is not changed unless the
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.Fl a
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flag is also specified.
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.It Fl r
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Use the access and modifications times from the specified file
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instead of the current time of day.
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.It Fl t
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Change the access and modification times to the specified time instead
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of the current time of day.
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The argument is of the form
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.Dq [[CC]YY]MMDDhhmm[.SS]
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where each pair of letters represents the following:
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.Pp
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.Bl -tag -width Ds -compact -offset indent
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.It Ar CC
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The first two digits of the year (the century).
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.It Ar YY
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The second two digits of the year.
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If
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.Dq YY
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is specified, but
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.Dq CC
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is not, a value for
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.Dq YY
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between 69 and 99 results in a
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.Dq CC
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value of 19.
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Otherwise, a
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.Dq CC
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value of 20 is used.
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.It Ar MM
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The month of the year, from 01 to 12.
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.It Ar DD
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the day of the month, from 01 to 31.
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.It Ar hh
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The hour of the day, from 00 to 23.
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.It Ar mm
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The minute of the hour, from 00 to 59.
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.It Ar SS
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The second of the minute, from 00 to 60.
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.El
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.Pp
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If the
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.Dq CC
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and
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.Dq YY
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letter pairs are not specified, the values default to the current
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year.
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If the
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.Dq SS
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letter pair is not specified, the value defaults to 0.
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.El
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.Sh EXIT STATUS
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.Ex -std
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.Sh COMPATIBILITY
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The obsolescent form of
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.Nm ,
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where a time format is specified as the first argument, is supported.
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When no
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.Fl r
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or
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.Fl t
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option is specified, there are at least two arguments, and the first
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argument is a string of digits either eight or ten characters in length,
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the first argument is interpreted as a time specification of the form
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.Dq MMDDhhmm[YY] .
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.Pp
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The
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.Dq MM ,
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.Dq DD ,
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.Dq hh
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and
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.Dq mm
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letter pairs are treated as their counterparts specified to the
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.Fl t
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option.
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If the
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.Dq YY
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letter pair is in the range 39 to 99, the year is set to 1939 to 1999,
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otherwise, the year is set in the 21st century.
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.Sh SEE ALSO
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.Xr utimensat 2
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.Sh STANDARDS
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The
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.Nm
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utility is expected to be a superset of the
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.St -p1003.2
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specification.
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.Sh HISTORY
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A
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.Nm
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utility appeared in
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.At v7 .
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