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.\" Copyright (c) 2003 Gunnar Ritter
.\"
.\" This software is provided 'as-is', without any express or implied
.\" warranty. In no event will the authors be held liable for any damages
.\" arising from the use of this software.
.\"
.\" Permission is granted to anyone to use this software for any purpose,
.\" including commercial applications, and to alter it and redistribute
.\" it freely, subject to the following restrictions:
.\"
.\" 1. The origin of this software must not be misrepresented; you must not
.\"    claim that you wrote the original software. If you use this software
.\"    in a product, an acknowledgment in the product documentation would be
.\"    appreciated but is not required.
.\"
.\" 2. Altered source versions must be plainly marked as such, and must not be
.\"    misrepresented as being the original software.
.\"
.\" 3. This notice may not be removed or altered from any source distribution.
.\" Sccsid @(#)date.1	1.16 (gritter) 1/24/05
.TH DATE 1 "1/24/05" "Heirloom Toolchest" "User Commands"
.SH NAME
date \- print or set the date
.SH SYNOPSIS
\fBdate\fR [\fB\-u\fR] [\fB+\fIformat\fR]
.br
\fBdate\fR [\fB\-u\fR] [\fB\-b\fR]
\fIHHMM\fR | \fImmddHHMM\fR[[\fIcc\fR]\fIyy\fR]
.br
\fBdate\fR \fB\-a\fR [\fB\-\fR]\fIsss.fff\fR
.SH DESCRIPTION
.B
Date
displays the current date if invoked without arguments
or with a
.BI + format
argument.
.PP
If the first argument does not start with
.BR + ,
.B date
sets the system time to the given value,
which may consist of
.sp
.RS
.TS
lfB l.
mm	month of year (01\^\(en\^12)
dd	day of month (01\^\(en\^31)
HH	hour (00\^\(en\^23)
MM	minute (00\^\(en\^59)
cc	first two digits of year
yy	second two digits of year
.TE
.RE
.PP
The following options alter the behavior of
.BR date :
.TP
\fB\-a\fR [\fI\-\fR]\fIsss.fff\fR
Adjust the system clock by
.I sss
seconds and
.I fff
milliseconds,
speeding up or,
with
.IR \-,
slowing down.
.TP
.B \-u
Use
.SM UTC
values for printing and setting the date.
.PP
The following option is an extension:
.TP
.B \-b
Causes
.I date
not to alter the `wtmp' file for the system time change.
.PP
An argument starting with
.B +
specifies a format string to print the current date.
A percent character
.B %
introduces a field descriptor with one or two following characters
which is replaced by a part of the current date,
as shown in the table below.
Other characters are printed literally.
A newline character is printed at the end of the output.
.TP
Field descriptors:
.TS
l3 l.
a	T{
locale-specific abbreviated weekday name (System\ III)
T}
.\" the following line implies the minimum table width
A	locale-specific full weekday name (SVID3, POSIX.2)
b	T{
locale-specific abbreviated month name (SVID3, POSIX.2)
T}
B	T{
locale-specific full month name (SVID3, POSIX.2)
T}
c	T{
locale-specific date and time (SVID3, POSIX.2)
T}
C	T{
century \(en 19 or 20 (POSIX.2) (\fB/usr/5bin/s42/date\fR, \fB/usr/5bin/posix/date\fR, \fB/usr/5bin/posix2001/date\fR)
.br
default output format (\fB/usr/5bin/date\fR)
T}
d	T{
day of month \(en 01 to 31 (System\ III)
T}
D	T{
date as mm/dd/yy (System\ III)
T}
e	T{
day of month \(en 1 to 31 (SVID3, POSIX.2)
T}
F	T{
date as yyyy\-mm\-dd
T}
g	T{
week-based year within century \(en 00 to 99
T}
G	T{
week-based year including century \(en 0000 to 9999
T}
h	T{
same as %b (System\ III)
T}
H	T{
hour \(en 00 to 23 (System\ III)
T}
I	T{
hour \(en 01 to 12 (SVID3, POSIX.2)
T}
j	T{
day of year \(en 001 to 366 (System\ III)
T}
m	T{
month of year \(en 01 to 12 (System\ III)
T}
M	T{
minute \(en 00 to 59 (System\ III)
T}
n	T{
newline character (System\ III)
T}
N	T{
default output format
T}
p	T{
locale-specific AM\^/\^PM string (SVID3, POSIX.2)
T}
r	T{
locale-specific time using AM\^/\^PM notation (System\ III)
T}
R	T{
same as %H:%M (SVID3)
T}
S	T{
second \(en 00 to 61 (System\ III)
T}
t	T{
tab character (System\ III)
T}
T	T{
time as HH:MM:SS (System\ III)
T}
u	T{
weekday \(en 1 (Monday) to 7 (POSIX.2)
T}
U	T{
week of year (Sunday as first day of week) \(en 00 to 53 (SVID3, POSIX.2)
T}
V	T{
week of year (Monday as first day of week) \(en 01 to 53 (POSIX.2)
T}
w	T{
weekday \(en 0 (Sunday) to 6 (System\ III)
T}
W	T{
week of year (Monday as first day of week) \(en 00 to 53 (SVID3, POSIX.2)
T}
x	T{
locale-specific date (POSIX.2)
T}
X	T{
locale-specific time (SVID3, POSIX.2)
T}
y	T{
last two digits of year \(en 00 to 99 (System\ III)
T}
Y	T{
four-digit year \(en 1970 to 2037 (SVID3, POSIX.2)
T}
z	T{
numeric timezone
T}
Z	T{
timezone name (SVID3, POSIX.2)
T}
%	T{
percent sign (System\ III)
T}
Ec	T{
alternative date and time (POSIX.2)
T}
EC	T{
alternative base year (period) (POSIX.2)
T}
Ex	T{
alternative date (POSIX.2)
T}
EX	T{
alternative time (SUSv2)
T}
Ey	T{
offset from %EC in years (POSIX.2)
T}
EY	T{
full alternative year (POSIX.2)
T}
Od	T{
day of month filled with leading zero using alternative numerals (POSIX.2)
T}
Oe	T{
day of month filled with leading space using alternative numerals (POSIX.2)
T}
OH	T{
24-hour clok using alternative numerals (POSIX.2)
T}
OI	T{
12-hour clock using alternative numerals (POSIX.2)
T}
Om	T{
month of year using alternative numerals (POSIX.2)
T}
OM	T{
minute using alternative numerals (POSIX.2)
T}
OS	T{
second using alternative numerals (POSIX.2)
T}
Ou	T{
weekday (Monday = 1) using alternative numerals (POSIX.2)
T}
OU	T{
week of year (cf. %U) using alternative numerals (POSIX.2)
T}
OV	T{
week of year (cf. %V) using alternative numerals (POSIX.2)
T}
Ow	T{
weekday (Sunday = 0) using alternative numerals (POSIX.2)
T}
OW	T{
week of year (cf. %W) using alternative numerals (POSIX.2)
T}
Oy	T{
year (offset from %C) using alternative numerals (POSIX.2)
T}
.TE
.TP
Compatibility references:
.TS
l l.
.\" the following line implies the minimum table width
System III	AT&T System III manual page date(1).\ \ \ \ \ \ 
SVID3	T{
AT&T System V Interface Definition, Third Edition, Volume II, 1992,
date(BU_CMD). Includes all field descriptors present in System III.
T}
POSIX.2	T{
ISO/IEC 9945-2:1993(E), 4.15.4.1\^\(en\^4.15.4.2, pp. 241\^\(en\^242.
Includes all field descriptors present in System III.
T}
SUSv2	T{
The Open Group,
Single \s-1UNIX\s0
Specification, Version 2, \(co 1997, date(XCU).
Includes all field descriptors present in POSIX.2.
T}
.TE
.PP
When no arguments are given,
the format defaults to
.RS
.sp
%a %b %e %H:%M:%S %Z %Y
.sp
.RE
in the C or POSIX locale, resulting in an output like
.RS
.sp
Wed Feb 26 17:48:54 CET 2003
.sp
.RE
.SH "ENVIRONMENT VARIABLES"
.TP
.B "LANG, LC_ALL"
See
.IR locale (7).
.TP
.B LC_TIME
Alters the strings printed when format arguments are given.
.TP
.B TZ
Timezone; if unset, the system default is used.
.SH "SEE ALSO"
adjtime(2),
stime(2),
strftime(3),
locale(7)
.SH NOTES
After setting the date,
the
.IR hwclock (8)
utility is called to adjust the hardware clock on Linux systems.