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. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" from: @(#)strftime.3 5.12 (Berkeley) 6/29/91 33.\" $OpenBSD: strftime.3,v 1.27 2011/09/16 19:36:07 jmc Exp $ 34.\" 35.Dd $Mdocdate: September 16 2011 $ 36.Dt STRFTIME 3 37.Os 38.Sh NAME 39.Nm strftime 40.Nd format date and time 41.Sh SYNOPSIS 42.Fd #include <time.h> 43.Ft size_t 44.Fn strftime "char *buf" "size_t maxsize" "const char *format" "const struct tm *timeptr" 45.Sh DESCRIPTION 46The 47.Fn strftime 48function formats the information from 49.Fa timeptr 50into the buffer 51.Fa buf 52according to the string pointed to by 53.Fa format . 54.Pp 55The 56.Fa format 57string consists of zero or more conversion specifications and 58ordinary characters. 59All ordinary characters are copied directly into the buffer. 60A conversion specification consists of a percent sign 61.Ql % 62and one other character. 63.Pp 64No more than 65.Fa maxsize 66characters will be placed into the array. 67If the total number of resulting characters, including the terminating 68NUL character, is not more than 69.Fa maxsize , 70.Fn strftime 71returns the number of characters in the array, not counting the 72terminating NUL. 73Otherwise, zero is returned. 74.Pp 75Each conversion specification is replaced by the characters as 76follows which are then copied into the buffer. 77.Bl -tag -width "xxxx" 78.It Cm \&%A 79is replaced by the locale's full weekday name. 80.It Cm \&%a 81is replaced by the locale's abbreviated weekday name. 82.It Cm \&%B 83is replaced by the locale's full month name. 84.It Cm \&%b No or Cm \&%h 85is replaced by the locale's abbreviated month name. 86.It Cm \&%C 87is replaced by the century (a year divided by 100 and truncated to an integer) 88as a decimal number (00\-99). 89.It Cm \&%c 90is replaced by the locale's appropriate date and time representation. 91.It Cm \&%D 92is replaced by the date in the format 93.Dq Li %m/%d/%y . 94.It Cm \&%d 95is replaced by the day of the month as a decimal number (01\-31). 96.It Cm \&%e 97is replaced by the day of month as a decimal number (1\-31); 98single digits are preceded by a blank. 99.It Cm \&%F 100is replaced by the date in the format 101.Dq Li %Y-%m-%d . 102.It Cm \&%G 103is replaced by the 104.St -iso8601 105year with century as a decimal number. 106.It Cm \&%g 107is replaced by the 108.St -iso8601 109year without century as a decimal number (00\-99). 110.It Cm \&%H 111is replaced by the hour (24-hour clock) as a decimal number (00\-23). 112.It Cm \&%I 113is replaced by the hour (12-hour clock) as a decimal number (01\-12). 114.It Cm \&%j 115is replaced by the day of the year as a decimal number (001\-366). 116.It Cm \&%k 117is replaced by the hour (24-hour clock) as a decimal number (0\-23); 118single digits are preceded by a blank. 119.It Cm \&%l 120is replaced by the hour (12-hour clock) as a decimal number (1\-12); 121single digits are preceded by a blank. 122.It Cm \&%M 123is replaced by the minute as a decimal number (00\-59). 124.It Cm %m 125is replaced by the month as a decimal number (01\-12). 126.It Cm %n 127is replaced by a newline. 128.It Cm %p 129is replaced by the locale's equivalent of either 130.Dq Tn AM 131or 132.Dq Tn PM . 133.It Cm \&%R 134is replaced by the time in the format 135.Dq Li %H:%M . 136.It Cm \&%r 137is replaced by the locale's representation of 12-hour clock time 138using AM/PM notation. 139.It Cm \&%S 140is replaced by the second as a decimal number (00\-60). 141The range of 142seconds is (00\-60) instead of (00\-59) to allow for the periodic occurrence 143of leap seconds. 144.It Cm %s 145is replaced by the number of seconds since the Epoch, UTC (see 146.Xr mktime 3 ) . 147.It Cm \&%T 148is replaced by the time in the format 149.Dq Li %H:%M:%S . 150.It Cm \&%t 151is replaced by a tab. 152.It Cm \&%U 153is replaced by the week number of the year (Sunday as the first day of 154the week) as a decimal number (00\-53). 155.It Cm \&%u 156is replaced by the weekday (Monday as the first day of the week) 157as a decimal number (1\-7). 158.It Cm \&%V 159is replaced by the week number of the year (Monday as the first day of 160the week) as a decimal number (01\-53). 161If the week containing January 1621 has four or more days in the new year, then it is week 1; otherwise 163it is week 53 of the previous year, and the next week is week 1. 164.It Cm \&%v 165is replaced by the date in the format 166.Dq Li "%e-%b-%Y" . 167.It Cm \&%W 168is replaced by the week number of the year (Monday as the first day of 169the week) as a decimal number (00\-53). 170.It Cm \&%w 171is replaced by the weekday (Sunday as the first day of the week) 172as a decimal number (0\-6). 173.It Cm \&%X 174is replaced by the locale's appropriate time representation. 175.It Cm \&%x 176is replaced by the locale's appropriate date representation. 177.It Cm \&%Y 178is replaced by the year with century as a decimal number. 179.It Cm \&%y 180is replaced by the year without century as a decimal number (00\-99). 181.It Cm \&%Z 182is replaced by the time zone name, 183or by the empty string if this is not determinable. 184.It Cm \&%z 185is replaced by the offset from UTC in the format 186.Dq Li +HHMM 187or 188.Dq Li -HHMM 189as appropriate, with positive values representing locations east 190of Greenwich, or by the empty string if this is not determinable. 191.It Cm %% 192is replaced by 193.Ql % . 194.It Cm %+ 195is replaced by the date and time in 196.Xr date 1 197format. 198.El 199.Sh SEE ALSO 200.Xr date 1 , 201.Xr printf 1 , 202.Xr ctime 3 , 203.Xr getenv 3 , 204.Xr printf 3 , 205.Xr strptime 3 , 206.Xr time 3 , 207.Xr tzset 3 , 208.Xr tzfile 5 209.Sh STANDARDS 210The 211.Fn strftime 212function 213conforms to 214.St -ansiC . 215.Pp 216The 217.Ql \&%G , 218.Ql \&%g , 219.Ql \&%k , 220.Ql \&%l , 221.Ql \&%s , 222.Ql \&%v , 223and 224.Ql \&%+ 225conversion specifications are extensions. 226.Pp 227Use of the 228.St -iso8601 229conversions may produce non-intuitive results. 230Week 01 of a year is per definition the first week which has the Thursday 231in this year, which is equivalent to the week which contains the fourth 232day of January. 233In other words, the first week of a new year is the week which has the 234majority of its days in the new year. 235Week 01 might also contain days from the previous year and the week 236before week 01 of a year is the last week (52 or 53) of the previous 237year even if it contains days from the new year. 238A week starts with Monday (day 1) and ends with Sunday (day 7). 239For example, the first week of the year 1997 lasts from 2401996-12-30 to 1997-01-05. 241.Sh BUGS 242There is no conversion specification for the phase of the moon. 243.Pp 244Note that while this implementation of 245.Fn strftime 246will always NUL terminate 247.Fa buf , 248other implementations may not do so when 249.Fa maxsize 250is not large enough to store the entire time string. 251The contents of 252.Fa buf 253are implementation specific in this case. 254.\" @(#)newstrftime.3 8.2 255