fbbd9655e5
Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96
290 lines
8.1 KiB
Groff
290 lines
8.1 KiB
Groff
.\" Copyright (c) 1989, 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 American National Standards Committee X3, on Information
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.\" Processing Systems.
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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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.\" @(#)strftime.3 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd June 25, 2012
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.Dt STRFTIME 3
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.Os
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.Sh NAME
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.Nm strftime
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.Nd format date and time
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In time.h
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.Ft size_t
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.Fo strftime
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.Fa "char * restrict buf"
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.Fa "size_t maxsize"
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.Fa "const char * restrict format"
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.Fa "const struct tm * restrict timeptr"
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.Fc
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.Ft size_t
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.Fn strftime_l "char *restrict buf" "size_t maxsize" "const char * restrict format" "const struct tm *restrict timeptr" "locale_t loc"
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.Sh DESCRIPTION
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The
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.Fn strftime
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function formats the information from
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.Fa timeptr
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into the buffer
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.Fa buf
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according to the string pointed to by
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.Fa format .
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The function
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.Fn strftime_l
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does the same as
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.Fn strftime
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but takes an explicit locale rather than using the current locale.
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.Pp
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The
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.Fa format
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string consists of zero or more conversion specifications and
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ordinary characters.
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All ordinary characters are copied directly into the buffer.
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A conversion specification consists of a percent sign
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.Dq Ql %
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and one other character.
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.Pp
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No more than
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.Fa maxsize
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characters will be placed into the array.
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If the total number of resulting characters, including the terminating
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NUL character, is not more than
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.Fa maxsize ,
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.Fn strftime
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returns the number of characters in the array, not counting the
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terminating NUL.
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Otherwise, zero is returned and the buffer contents are indeterminate.
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.Pp
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The conversion specifications are copied to the buffer after expansion
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as follows:-
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.Bl -tag -width "xxxx"
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.It Cm \&%A
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is replaced by national representation of the full weekday name.
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.It Cm %a
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is replaced by national representation of
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the abbreviated weekday name.
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.It Cm \&%B
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is replaced by national representation of the full month name.
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.It Cm %b
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is replaced by national representation of
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the abbreviated month name.
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.It Cm \&%C
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is replaced by (year / 100) as decimal number; single
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digits are preceded by a zero.
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.It Cm %c
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is replaced by national representation of time and date.
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.It Cm \&%D
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is equivalent to
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.Dq Li %m/%d/%y .
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.It Cm %d
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is replaced by the day of the month as a decimal number (01-31).
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.It Cm %E* %O*
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POSIX locale extensions.
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The sequences
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%Ec %EC %Ex %EX %Ey %EY
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%Od %Oe %OH %OI %Om %OM
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%OS %Ou %OU %OV %Ow %OW %Oy
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are supposed to provide alternate
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representations.
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.Pp
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Additionally %OB implemented
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to represent alternative months names
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(used standalone, without day mentioned).
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.It Cm %e
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is replaced by the day of the month as a decimal number (1-31); single
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digits are preceded by a blank.
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.It Cm \&%F
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is equivalent to
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.Dq Li %Y-%m-%d .
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.It Cm \&%G
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is replaced by a year as a decimal number with century.
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This year is the one that contains the greater part of
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the week (Monday as the first day of the week).
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.It Cm %g
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is replaced by the same year as in
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.Dq Li %G ,
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but as a decimal number without century (00-99).
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.It Cm \&%H
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is replaced by the hour (24-hour clock) as a decimal number (00-23).
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.It Cm %h
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the same as
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.Cm %b .
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.It Cm \&%I
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is replaced by the hour (12-hour clock) as a decimal number (01-12).
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.It Cm %j
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is replaced by the day of the year as a decimal number (001-366).
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.It Cm %k
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is replaced by the hour (24-hour clock) as a decimal number (0-23);
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single digits are preceded by a blank.
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.It Cm %l
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is replaced by the hour (12-hour clock) as a decimal number (1-12);
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single digits are preceded by a blank.
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.It Cm \&%M
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is replaced by the minute as a decimal number (00-59).
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.It Cm %m
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is replaced by the month as a decimal number (01-12).
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.It Cm %n
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is replaced by a newline.
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.It Cm %O*
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the same as
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.Cm %E* .
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.It Cm %p
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is replaced by national representation of either
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"ante meridiem" (a.m.)
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or
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"post meridiem" (p.m.)
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as appropriate.
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.It Cm \&%R
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is equivalent to
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.Dq Li %H:%M .
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.It Cm %r
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is equivalent to
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.Dq Li %I:%M:%S %p .
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.It Cm \&%S
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is replaced by the second as a decimal number (00-60).
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.It Cm %s
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is replaced by the number of seconds since the Epoch, UTC (see
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.Xr mktime 3 ) .
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.It Cm \&%T
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is equivalent to
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.Dq Li %H:%M:%S .
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.It Cm %t
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is replaced by a tab.
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.It Cm \&%U
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is replaced by the week number of the year (Sunday as the first day of
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the week) as a decimal number (00-53).
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.It Cm %u
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is replaced by the weekday (Monday as the first day of the week)
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as a decimal number (1-7).
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.It Cm \&%V
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is replaced by the week number of the year (Monday as the first day of
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the week) as a decimal number (01-53).
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If the week containing January
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1 has four or more days in the new year, then it is week 1; otherwise
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it is the last week of the previous year, and the next week is week 1.
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.It Cm %v
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is equivalent to
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.Dq Li %e-%b-%Y .
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.It Cm \&%W
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is replaced by the week number of the year (Monday as the first day of
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the week) as a decimal number (00-53).
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.It Cm %w
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is replaced by the weekday (Sunday as the first day of the week)
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as a decimal number (0-6).
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.It Cm \&%X
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is replaced by national representation of the time.
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.It Cm %x
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is replaced by national representation of the date.
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.It Cm \&%Y
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is replaced by the year with century as a decimal number.
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.It Cm %y
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is replaced by the year without century as a decimal number (00-99).
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.It Cm \&%Z
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is replaced by the time zone name.
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.It Cm %z
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is replaced by the time zone offset from UTC; a leading plus sign stands for
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east of UTC, a minus sign for west of UTC, hours and minutes follow
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with two digits each and no delimiter between them (common form for
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RFC 822 date headers).
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.It Cm %+
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is replaced by national representation of the date and time
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(the format is similar to that produced by
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.Xr date 1 ) .
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.It Cm %-*
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GNU libc extension.
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Do not do any padding when performing numerical outputs.
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.It Cm %_*
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GNU libc extension.
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Explicitly specify space for padding.
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.It Cm %0*
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GNU libc extension.
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Explicitly specify zero for padding.
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.It Cm %%
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is replaced by
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.Ql % .
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.El
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.Sh SEE ALSO
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.Xr date 1 ,
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.Xr printf 1 ,
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.Xr ctime 3 ,
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.Xr printf 3 ,
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.Xr strptime 3 ,
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.Xr wcsftime 3
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.Sh STANDARDS
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The
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.Fn strftime
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function
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conforms to
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.St -isoC
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with a lot of extensions including
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.Ql \&%C ,
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.Ql \&%D ,
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.Ql %E* ,
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.Ql %e ,
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.Ql %G ,
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.Ql %g ,
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.Ql %h ,
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.Ql %k ,
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.Ql %l ,
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.Ql %n ,
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.Ql %O* ,
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.Ql \&%R ,
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.Ql %r ,
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.Ql %s ,
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.Ql \&%T ,
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.Ql %t ,
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.Ql %u ,
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.Ql \&%V ,
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.Ql %z ,
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.Ql %+ .
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.Pp
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The peculiar week number and year in the replacements of
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.Ql %G ,
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.Ql %g
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and
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.Ql \&%V
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are defined in ISO 8601: 1988.
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The
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.Fn strftime_l
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function conforms to
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.St -p1003.1-2008 .
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.Sh BUGS
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There is no conversion specification for the phase of the moon.
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.Pp
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The
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.Fn strftime
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function does not correctly handle multibyte characters in the
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.Fa format
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argument.
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