1.\" Copyright (c) 1989, 1991, 1993 2.\" The Regents of the University of California. 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.\" @(#)strftime.3 8.1 (Berkeley) 6/4/93 37.\" 38.Dd June 4, 1993 39.Dt STRFTIME 3 40.Os 41.Sh NAME 42.Nm strftime 43.Nd format date and time 44.Sh SYNOPSIS 45.Fd #include <time.h> 46.Ft size_t 47.Fn strftime "char *buf" "size_t maxsize" "const char *format" "const struct tm *timeptr" 48.Sh DESCRIPTION 49The 50.Fn strftime 51function formats the information from 52.Fa timeptr 53into the buffer 54.Fa buf 55according to the string pointed to by 56.Fa format . 57.Pp 58The 59.Fa format 60string consists of zero or more conversion specifications and 61ordinary characters. 62All ordinary characters are copied directly into the buffer. 63A conversion specification consists of a percent sign 64.Dq Ql % 65and one other character. 66.Pp 67No more than 68.Fa maxsize 69characters will be placed into the array. If more characters than 70.Fa maxsize 71could have been written into 72.Fa buf 73then 74.Fa bug 75will not be 76.Sq Li \&\e0 77terminated. 78If the total number of resulting characters, including the terminating 79.Sq Li \&\e0 80character, is not more than 81.Fa maxsize , 82.Fn strftime 83returns the number of characters in the array, not counting the 84terminating 85.Sq Li \&\e0 . 86Otherwise, zero is returned. 87.Pp 88Each conversion specification is replaced by the characters as 89follows which are then copied into the buffer. 90.Bl -tag -width "xxxx" 91.It Cm \&%A 92is replaced by national representation of the full weekday name. 93.It Cm %a 94is replaced by national representation of 95the abbreviated weekday name, where the abbreviation 96is the first three characters. 97.It Cm \&%B 98is replaced by national representation of the full month name. 99.It Cm %b 100is replaced by national representation of 101the abbreviated month name, where the abbreviation is 102the first three characters. 103.It Cm \&%C 104is replaced by (year / 100) as decimal number; single 105digits are preceded by a zero. 106.It Cm %c 107is replaced by national representation of time and date 108(the format is similar with produced by 109.Xr asctime 3 ) . 110.It Cm \&%D 111is equivalent to 112.Dq Li %m/%d/%y . 113.It Cm %d 114is replaced by the day of the month as a decimal number (01-31). 115.It Cm \&%E* 116POSIX locale extensions. 117The sequences 118%Ec %EC %Ex %Ey %EY 119%Od %Oe %OH %OI %Om %OM 120%OS %Ou %OU %OV %Ow %OW %Oy 121are supposed to provide alternate 122representations. 123.It Cm %e 124is replaced by the day of month as a decimal number (1-31); single 125digits are preceded by a blank. 126.It Cm \&%H 127is replaced by the hour (24-hour clock) as a decimal number (00-23). 128.It Cm %h 129the same as %b. 130.It Cm \&%I 131is replaced by the hour (12-hour clock) as a decimal number (01-12). 132.It Cm %j 133is replaced by the day of the year as a decimal number (001-366). 134.It Cm %k 135is replaced by the hour (24-hour clock) as a decimal number (0-23); 136single digits are preceded by a blank. 137.It Cm %l 138is replaced by the hour (12-hour clock) as a decimal number (1-12); 139single digits are preceded by a blank. 140.It Cm \&%M 141is replaced by the minute as a decimal number (00-59). 142.It Cm %m 143is replaced by the month as a decimal number (01-12). 144.It Cm %n 145is replaced by a newline. 146.It Cm \&%O* 147the same as %E*. 148.It Cm %p 149is replaced by national representation of either 150"ante meridiem" 151or 152"post meridiem" 153as appropriate. 154.It Cm \&%R 155is equivalent to 156.Dq Li %H:%M . 157.It Cm %r 158is equivalent to 159.Dq Li %I:%M:%S %p . 160.It Cm \&%S 161is replaced by the second as a decimal number (00-60). 162.It Cm %s 163is replaced by the number of seconds since the Epoch, UTC (see 164.Xr mktime 3 ) . 165.It Cm \&%T 166is equivalent to 167.Dq Li %H:%M:%S . 168.It Cm %t 169is replaced by a tab. 170.It Cm \&%U 171is replaced by the week number of the year (Sunday as the first day of 172the week) as a decimal number (00-53). 173.It Cm %u 174is replaced by the weekday (Monday as the first day of the week) 175as a decimal number (1-7). 176.It Cm \&%V 177is replaced by the week number of the year (the first 178Monday as the first day of week 1) as a 179decimal number (01-53). 180.It Cm %v 181is equivalent to 182.Dq Li %e-%b-%Y . 183.It Cm \&%W 184is replaced by the week number of the year (Monday as the first day of 185the week) as a decimal number (00-53). 186.It Cm %w 187is replaced by the weekday (Sunday as the first day of the week) 188as a decimal number (0-6). 189.It Cm \&%X 190is replaced by national representation of the time. 191.It Cm %x 192is replaced by national representation of the date. 193.It Cm \&%Y 194is replaced by the year with century as a decimal number. 195.It Cm %y 196is replaced by the year without century as a decimal number (00-99). 197.It Cm \&%Z 198is replaced by the time zone name. 199.It Cm %+ 200is replaced by national representation of the date and time 201(the format is similar with produced by 202.Xr date 1 ) . 203.It Cm %% 204is replaced by 205.Ql % . 206.El 207.Sh SEE ALSO 208.Xr date 1 , 209.Xr printf 1 , 210.Xr ctime 3 , 211.Xr printf 3 212.Sh STANDARDS 213The 214.Fn strftime 215function 216conforms to 217.St -ansiC . 218The 219.Ql %s 220conversion specification is an extension. 221.Sh BUGS 222There is no conversion specification for the phase of the moon. 223