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. 101The format is similar to that produced by 102.Xr ctime 3 103and is 104equivalent to "%a %Ef %T %Y". 105It also implies the 106"3+1+6+1+8+1+4" format of output. 107.It Cm \&%D 108is equivalent to 109.Dq Li %m/%d/%y . 110.It Cm %d 111is replaced by the day of the month as a decimal number (01-31). 112.It Cm \&%E* Cm \&%O* 113POSIX locale extensions. 114The sequences 115%Ec %EC %Ex %EX %Ey %EY 116%Od %Oe %OH %OI %Om %OM 117%OS %Ou %OU %OV %Ow %OW %Oy 118are supposed to provide alternate 119representations. 120.Pp 121Additionly %Ef implemented to represent short month name / day 122order of the date, %EF to represent long month name / day 123order 124and %OB to represent alternative months names 125(used standalone, without day mentioned). 126.It Cm %e 127is replaced by the day of month as a decimal number (1-31); single 128digits are preceded by a blank. 129.It Cm \&%G 130is replaced by a year as a decimal number with century. 131This year is the one that contains the greater part of 132the week (Monday as the first day of the week). 133.It Cm %g 134is replaced by the same year as in 135.Dq Li %G , 136but as a decimal number without century (00-99). 137.It Cm \&%H 138is replaced by the hour (24-hour clock) as a decimal number (00-23). 139.It Cm %h 140the same as %b. 141.It Cm \&%I 142is replaced by the hour (12-hour clock) as a decimal number (01-12). 143.It Cm %j 144is replaced by the day of the year as a decimal number (001-366). 145.It Cm %k 146is replaced by the hour (24-hour clock) as a decimal number (0-23); 147single digits are preceded by a blank. 148.It Cm %l 149is replaced by the hour (12-hour clock) as a decimal number (1-12); 150single digits are preceded by a blank. 151.It Cm \&%M 152is replaced by the minute as a decimal number (00-59). 153.It Cm %m 154is replaced by the month as a decimal number (01-12). 155.It Cm %n 156is replaced by a newline. 157.It Cm \&%O* 158the same as %E*. 159.It Cm %p 160is replaced by national representation of either 161"ante meridiem" 162or 163"post meridiem" 164as appropriate. 165.It Cm \&%R 166is equivalent to 167.Dq Li %H:%M . 168.It Cm %r 169is equivalent to 170.Dq Li %I:%M:%S %p . 171.It Cm \&%S 172is replaced by the second as a decimal number (00-60). 173.It Cm %s 174is replaced by the number of seconds since the Epoch, UTC (see 175.Xr mktime 3 ) . 176.It Cm \&%T 177is equivalent to 178.Dq Li %H:%M:%S . 179.It Cm %t 180is replaced by a tab. 181.It Cm \&%U 182is replaced by the week number of the year (Sunday as the first day of 183the week) as a decimal number (00-53). 184.It Cm %u 185is replaced by the weekday (Monday as the first day of the week) 186as a decimal number (1-7). 187.It Cm \&%V 188is replaced by the week number of the year (Monday as the first day of 189the week) as a decimal number (01-53). If the week containing January 1901 has four or more days in the new year, then it is week 1; otherwise 191it is the last week of the previous year, and the next week is week 1. 192.It Cm %v 193is equivalent to 194.Dq Li %e-%b-%Y . 195.It Cm \&%W 196is replaced by the week number of the year (Monday as the first day of 197the week) as a decimal number (00-53). 198.It Cm %w 199is replaced by the weekday (Sunday as the first day of the week) 200as a decimal number (0-6). 201.It Cm \&%X 202is replaced by national representation of the time. 203.It Cm %x 204is replaced by national representation of the date. 205.It Cm \&%Y 206is replaced by the year with century as a decimal number. 207.It Cm %y 208is replaced by the year without century as a decimal number (00-99). 209.It Cm \&%Z 210is replaced by the time zone name. 211.It Cm \&%z 212is replaced by the time zone offset from UTC; a leading plus sign stands for 213east of UTC, a minus sign for west of UTC, hours and minutes follow 214with two digits each and no delimiter between them (common form for 215RFC 822 date headers). 216.It Cm %+ 217is replaced by national representation of the date and time 218(the format is similar to that produced by 219.Xr date 1 ) . 220.It Cm %% 221is replaced by 222.Ql % . 223.El 224.Sh SEE ALSO 225.Xr date 1 , 226.Xr printf 1 , 227.Xr ctime 3 , 228.Xr printf 3 , 229.Xr strptime 3 230.Sh STANDARDS 231The 232.Fn strftime 233function 234conforms to 235.St -ansiC 236with a lot of extensions including 237.Ql %C , 238.Ql %D , 239.Ql %E* , 240.Ql %e , 241.Ql %G , 242.Ql %g , 243.Ql %h , 244.Ql %k , 245.Ql %l , 246.Ql %n , 247.Ql %O* , 248.Ql \&%R , 249.Ql %r , 250.Ql %s , 251.Ql \&%T , 252.Ql %t , 253.Ql %u , 254.Ql \&%V , 255.Ql %z , 256.Ql %+ . 257 258The peculiar week number and year in the replacements of 259.Ql %G , 260.Ql %g 261and 262.Ql \&%V 263are defined in ISO 8601: 1988. 264 265.Sh BUGS 266There is no conversion specification for the phase of the moon. 267