1.\" Copyright (c) 1989, 1991 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the American National Standards Committee X3, on Information 6.\" Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" from: @(#)strftime.3 5.12 (Berkeley) 6/29/91 37.\" $NetBSD: strftime.3,v 1.15 2002/08/18 06:31:09 yamt Exp $ 38.\" 39.Dd August 18, 2002 40.Dt STRFTIME 3 41.Os 42.Sh NAME 43.Nm strftime 44.Nd format date and time 45.Sh LIBRARY 46.Lb libc 47.Sh SYNOPSIS 48.Fd #include \*[Lt]time.h\*[Gt] 49.Ft size_t 50.Fn strftime "char * restrict buf" "size_t maxsize" "const char * restrict format" "const struct tm * restrict timeptr" 51.Sh DESCRIPTION 52The 53.Fn strftime 54function formats the information from 55.Fa timeptr 56into the buffer 57.Fa buf 58according to the string pointed to by 59.Fa format . 60.Pp 61The 62.Fa format 63string consists of zero or more conversion specifications and 64ordinary characters. 65All ordinary characters are copied directly into the buffer. 66A conversion specification consists of a percent sign 67.Ql % 68and one other character. 69.Pp 70No more than 71.Fa maxsize 72characters will be placed into the array. 73If the total number of resulting characters, including the terminating 74null character, is not more than 75.Fa maxsize , 76.Fn strftime 77returns the number of characters in the array, not counting the 78terminating null. 79Otherwise, zero is returned and the contents of the array are undefined. 80.Pp 81Each conversion specification is replaced by the characters as 82follows which are then copied into the buffer. 83.Bl -tag -width "xxxx" 84.It Cm \&%A 85is replaced by the locale's full weekday name. 86.It Cm %a 87is replaced by the locale's abbreviated weekday name. 88.It Cm \&%B 89is replaced by the locale's full month name. 90.It Cm \&%b No or Cm \&%h 91is replaced by the locale's abbreviated month name. 92.It Cm \&%C 93is replaced by the century (a year divided by 100 and truncated to an integer) 94as a decimal number [00,99]. 95.It Cm \&%c 96is replaced by the locale's appropriate date and time representation. 97.It Cm \&%D 98is replaced by the date in the format 99.Dq Li %m/%d/%y . 100.It Cm \&%d 101is replaced by the day of the month as a decimal number [01,31]. 102.It Cm \&%e 103is replaced by the day of month as a decimal number [1,31]; 104single digits are preceded by a blank. 105.It Cm \&%F 106is replaced by the time in the format 107.Dq Li %Y-%m-%d 108(the ISO 8601 date format). 109.It Cm \&%G 110is replaced by the ISO 8601 year with century as a decimal number. 111.TP 112.It Cm \&%g 113is replaced by the ISO 8601 year without century as a decimal number (00-99). 114This is the year that includes the greater part of the week. (Monday as the 115first day of a week). See also the 116.Ql \&%V 117conversion specification. 118.TP 119.It Cm \&%H 120is replaced by the hour (24-hour clock) as a decimal number [00,23]. 121.It Cm \&%I 122is replaced by the hour (12-hour clock) as a decimal number [01,12]. 123.It Cm \&%j 124is replaced by the day of the year as a decimal number [001,366]. 125.It Cm \&%k 126is replaced by the hour (24-hour clock) as a decimal number [0,23]; 127single digits are preceded by a blank. 128.It Cm \&%l 129is replaced by the hour (12-hour clock) as a decimal number [1,12]; 130single digits are preceded by a blank. 131.It Cm \&%M 132is replaced by the minute as a decimal number [00,59]. 133.It Cm %m 134is replaced by the month as a decimal number [01,12]. 135.It Cm %n 136is replaced by a newline. 137.It Cm %p 138is replaced by the locale's equivalent of either 139.Dq Tn AM 140or 141.Dq Tn PM . 142.It Cm \&%R 143is replaced by the time in the format 144.Dq Li %H:%M . 145.It Cm \&%r 146is replaced by the locale's representation of 12-hour clock time 147using AM/PM notation. 148.It Cm \&%S 149is replaced by the second as a decimal number [00,61]. 150The range of 151seconds is (00-61) instead of (00-59) to allow for the periodic occurance 152of leap seconds and double leap seconds. 153.It Cm %s 154is replaced by the number of seconds since the Epoch, UCT (see 155.Xr mktime 3 ) . 156.It Cm \&%T 157is replaced by the time in the format 158.Dq Li %H:%M:%S . 159.It Cm \&%t 160is replaced by a tab. 161.It Cm \&%U 162is replaced by the week number of the year (Sunday as the first day of 163the week) as a decimal number [00,53]. 164.It Cm \&%u 165is replaced by the weekday (Monday as the first day of the week) 166as a decimal number [1,7]. 167.It Cm \&%V 168is replaced by the week number of the year (Monday as the first day of 169the week) as a decimal number [01,53]. According to ISO 8601 the week 170containing January 1 is week 1 if it has four or more days in the new year, 171otherwise it is week 53 of the previous year, and the next week is week 1. 172The year is given by the 173.Ql \&%G 174conversion specification. 175.It Cm \&%W 176is replaced by the week number of the year (Monday as the first day of 177the week) as a decimal number [00,53]. 178.It Cm \&%w 179is replaced by the weekday (Sunday as the first day of the week) 180as a decimal number [0,6]. 181.It Cm \&%X 182is replaced by the locale's appropriate time representation. 183.It Cm \&%x 184is replaced by the locale's appropriate date representation. 185.It Cm \&%Y 186is replaced by the year with century as a decimal number. 187.It Cm \&%y 188is replaced by the year without century as a decimal number [00,99]. 189.It Cm \&%Z 190is replaced by the time zone name. 191.It Cm \&%z 192is replaced by the offset from ITC in the ISO 8601 format 193.Dq Li [-]hhmm . 194.It Cm %% 195is replaced by 196.Ql % . 197.El 198.Sh SEE ALSO 199.Xr date 1 , 200.Xr printf 1 , 201.Xr ctime 3 , 202.Xr printf 3 , 203.Xr strptime 3 204.Sh STANDARDS 205The 206.Fn strftime 207function 208conforms to 209.St -isoC99 . 210The 211.Ql \&%C , 212.Ql \&%D , 213.Ql \&%e , 214.Ql \&%g , 215.Ql \&%G , 216.Ql \&%h , 217.Ql \&%k , 218.Ql \&%l , 219.Ql \&%n , 220.Ql \&%r , 221.Ql \&%R , 222.Ql \&%s , 223.Ql \&%t , 224.Ql \&%T , 225.Ql \&%u , 226and 227.Ql \&%V 228conversion specifications are extensions. 229.Pp 230Use of the ISO 8601 conversions may produce non-intuitive results. 231Week 01 of a year is per definition the first week which has the Thursday 232in this year, which is equivalent to the week which contains the fourth 233day of January. 234In other words, the first week of a new year is the week which has the 235majority of its days in the new year. 236Week 01 might also contain days from the previous year and the week 237before week 01 of a year is the last week (52 or 53) of the previous 238year even if it contains days from the new year. 239A week starts with Monday (day 1) and ends with Sunday (day 7). 240For example, the first week of the year 1997 lasts from 2411996-12-30 to 1997-01-05. 242.Sh BUGS 243There is no conversion specification for the phase of the moon. 244