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[thirdparty/man-pages.git] / man3 / strftime.3

.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
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.\" manual provided the copyright notice and this permission notice are
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.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
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.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\"     GNU texinfo documentation on glibc date/time functions.
.\" Modified Sat Jul 24 18:03:44 1993 by Rik Faith (faith@cs.unc.edu)
.\" Applied fix by Wolfgang Franke, aeb, 961011
.\" Corrected return value, aeb, 970307
.\" Added Single Unix Spec conversions and %z, aeb/esr, 990329.
.\" 2005-11-22 mtk, added Glibc Notes covering optional 'flag' and
.\"           'width' components of conversion specifications.
.\"
.TH STRFTIME 3  2010-01-17 "GNU" "Linux Programmer's Manual"
.SH NAME
strftime \- format date and time
.SH SYNOPSIS
.nf
.B #include <time.h>
.sp
.BI "size_t strftime(char *" s ", size_t " max ", const char *" format ,
.BI "                const struct tm *" tm );
.fi
.SH DESCRIPTION
The
.BR strftime ()
function formats the broken-down time \fItm\fP
according to the format specification \fIformat\fP and places the
result in the character array \fIs\fP of size \fImax\fP.
.\" FIXME POSIX says: Local timezone information is used as though
.\" strftime() called tzset().  But this doesn't appear to be the case
.PP
Ordinary characters placed in the format string are copied to \fIs\fP
without conversion.
.I "Conversion specifications"
are introduced by a \(aq%\(aq
character, and terminated by a
.IR "conversion specifier character" ,
and are replaced in \fIs\fP as follows:
.TP
.B %a
The abbreviated weekday name according to the current locale.
.TP
.B %A
The full weekday name according to the current locale.
.TP
.B %b
The abbreviated month name according to the current locale.
.TP
.B %B
The full month name according to the current locale.
.TP
.B %c
The preferred date and time representation for the current locale.
.TP
.B %C
The century number (year/100) as a 2-digit integer. (SU)
.TP
.B %d
The day of the month as a decimal number (range 01 to 31).
.TP
.B %D
Equivalent to
.BR %m/%d/%y .
(Yecch \(em for Americans only.
Americans should note that in other countries
.B %d/%m/%y
is rather common.
This means that in international context this format is
ambiguous and should not be used.) (SU)
.TP
.B %e
Like
.BR %d ,
the day of the month as a decimal number, but a leading
zero is replaced by a space. (SU)
.TP
.B %E
Modifier: use alternative format, see below. (SU)
.TP
.B %F
Equivalent to
.B %Y-%m-%d
(the ISO\ 8601 date format). (C99)
.TP
.B %G
The ISO\ 8601 week-based year (see NOTES) with century as a decimal number.
The 4-digit year corresponding to the ISO week number (see
.BR %V ).
This has the same format and value as
.BR %Y ,
except that if the ISO week number belongs to the previous or next year,
that year is used instead. (TZ)
.TP
.B %g
Like
.BR %G ,
but without century, that is, with a 2-digit year (00-99). (TZ)
.TP
.B %h
Equivalent to
.BR %b .
(SU)
.TP
.B %H
The hour as a decimal number using a 24-hour clock (range 00 to 23).
.TP
.B %I
The hour as a decimal number using a 12-hour clock (range 01 to 12).
.TP
.B %j
The day of the year as a decimal number (range 001 to 366).
.TP
.B %k
The hour (24-hour clock) as a decimal number (range 0 to 23);
single digits are preceded by a blank.
(See also
.BR %H .)
(TZ)
.TP
.B %l
The hour (12-hour clock) as a decimal number (range 1 to 12);
single digits are preceded by a blank.
(See also
.BR %I .)
(TZ)
.TP
.B %m
The month as a decimal number (range 01 to 12).
.TP
.B %M
The minute as a decimal number (range 00 to 59).
.TP
.B %n
A newline character. (SU)
.TP
.B %O
Modifier: use alternative format, see below. (SU)
.TP
.B %p
Either "AM" or "PM" according to the given time value, or the
corresponding strings for the current locale.