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.\" $FreeBSD$ 38.\" 39.Dd October 4, 1997 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 <time.h> 49.Ft size_t 50.Fn strftime "char *buf" "size_t maxsize" "const char *format" "const struct tm *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.Dq 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 74NUL character, is not more than 75.Fa maxsize , 76.Fn strftime 77returns the number of characters in the array, not counting the 78terminating NUL. 79Otherwise, zero is returned and the buffer contents is indeterminate. 80.Pp 81The conversion specifications are copied to the buffer after expansion 82as follows:- 83.Bl -tag -width "xxxx" 84.It Cm \&%A 85is replaced by national representation of the full weekday name. 86.It Cm %a 87is replaced by national representation of 88the abbreviated weekday name, where the abbreviation 89is the first three characters. 90.It Cm \&%B 91is replaced by national representation of the full month name. 92.It Cm %b 93is replaced by national representation of 94the abbreviated month name, where the abbreviation is 95the first three characters. 96.It Cm \&%C 97is replaced by (year / 100) as decimal number; single 98digits are preceded by a zero. 99.It Cm %c 100is replaced by national representation of time and date 101(the format is similar with produced by 102.Xr asctime 3 ) . 103.It Cm \&%D 104is equivalent to 105.Dq Li %m/%d/%y . 106.It Cm %d 107is replaced by the day of the month as a decimal number (01-31). 108.It Cm \&%E* Cm \&%O* 109POSIX locale extensions. 110The sequences 111%Ec %EC %Ex %EX %Ey %EY 112%Od %Oe %OH %OI %Om %OM 113%OS %Ou %OU %OV %Ow %OW %Oy 114are supposed to provide alternate 115representations. 116.Pp 117Additionly %Ef implemented to represent short month name / day 118order of the date, %EF to represent long month name / day 119order 120and %OB to represent alternative months names 121(used standalone, without day mentioned). 122.It Cm %e 123is replaced by the day of month as a decimal number (1-31); single 124digits are preceded by a blank. 125.It Cm \&%G 126is replaced by a year as a decimal number with century. 127This year is the one that contains the greater part of 128the week (Monday as the first day of the week). 129.It Cm %g 130is replaced by the same year as in 131.Dq Li %G , 132but as a decimal number without century (00-99). 133.It Cm \&%H 134is replaced by the hour (24-hour clock) as a decimal number (00-23). 135.It Cm %h 136the same as %b. 137.It Cm \&%I 138is replaced by the hour (12-hour clock) as a decimal number (01-12). 139.It Cm %j 140is replaced by the day of the year as a decimal number (001-366). 141.It Cm %k 142is replaced by the hour (24-hour clock) as a decimal number (0-23); 143single digits are preceded by a blank. 144.It Cm %l 145is replaced by the hour (12-hour clock) as a decimal number (1-12); 146single digits are preceded by a blank. 147.It Cm \&%M 148is replaced by the minute as a decimal number (00-59). 149.It Cm %m 150is replaced by the month as a decimal number (01-12). 151.It Cm %n 152is replaced by a newline. 153.It Cm \&%O* 154the same as %E*. 155.It Cm %p 156is replaced by national representation of either 157"ante meridiem" 158or 159"post meridiem" 160as appropriate. 161.It Cm \&%R 162is equivalent to 163.Dq Li %H:%M . 164.It Cm %r 165is equivalent to 166.Dq Li %I:%M:%S %p . 167.It Cm \&%S 168is replaced by the second as a decimal number (00-60). 169.It Cm %s 170is replaced by the number of seconds since the Epoch, UTC (see 171.Xr mktime 3 ) . 172.It Cm \&%T 173is equivalent to 174.Dq Li %H:%M:%S . 175.It Cm %t 176is replaced by a tab. 177.It Cm \&%U 178is replaced by the week number of the year (Sunday as the first day of 179the week) as a decimal number (00-53). 180.It Cm %u 181is replaced by the weekday (Monday as the first day of the week) 182as a decimal number (1-7). 183.It Cm \&%V 184is replaced by the week number of the year (Monday as the first day of 185the week) as a decimal number (01-53). If the week containing January 1861 has four or more days in the new year, then it is week 1; otherwise 187it is the last week of the previous year, and the next week is week 1. 188.It Cm %v 189is equivalent to 190.Dq Li %e-%b-%Y . 191.It Cm \&%W 192is replaced by the week number of the year (Monday as the first day of 193the week) as a decimal number (00-53). 194.It Cm %w 195is replaced by the weekday (Sunday as the first day of the week) 196as a decimal number (0-6). 197.It Cm \&%X 198is replaced by national representation of the time. 199.It Cm %x 200is replaced by national representation of the date. 201.It Cm \&%Y 202is replaced by the year with century as a decimal number. 203.It Cm %y 204is replaced by the year without century as a decimal number (00-99). 205.It Cm \&%Z 206is replaced by the time zone name. 207.It Cm \&%z 208is replaced by the time zone offset from UTC; a leading plus sign stands for 209east of UTC, a minus sign for west of UTC, hours and minutes follow 210with two digits each and no delimiter between them (common form for 211RFC 822 date headers). 212.It Cm %+ 213is replaced by national representation of the date and time 214(the format is similar to that produced by 215.Xr date 1 ) . 216.It Cm %% 217is replaced by 218.Ql % . 219.El 220.Sh SEE ALSO 221.Xr date 1 , 222.Xr printf 1 , 223.Xr ctime 3 , 224.Xr printf 3 , 225.Xr strptime 3 226.Sh STANDARDS 227The 228.Fn strftime 229function 230conforms to 231.St -ansiC 232with a lot of extensions including 233.Ql %C , 234.Ql %D , 235.Ql %E* , 236.Ql %e , 237.Ql %G , 238.Ql %g , 239.Ql %h , 240.Ql %k , 241.Ql %l , 242.Ql %n , 243.Ql %O* , 244.Ql \&%R , 245.Ql %r , 246.Ql %s , 247.Ql \&%T , 248.Ql %t , 249.Ql %u , 250.Ql \&%V , 251.Ql %z , 252.Ql %+ . 253 254The peculiar week number and year in the replacements of 255.Ql %G , 256.Ql %g 257and 258.Ql \&%V 259are defined in ISO 8601: 1988. 260 261.Sh BUGS 262There is no conversion specification for the phase of the moon. 263