date (1p) - Linux Manuals
date: write the date and time
PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.NAME
date - write the date and time
SYNOPSIS
date [-u] [+format]
DESCRIPTION
The date utility shall write the date and time to standard output
The date utility shall conform to the Base Definitions volume
of IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
The following option shall be supported:
The following operands shall be supported:
See the Base Definitions volume of IEEE Std 1003.1-2001, Section
7.3.5, LC_TIME for the conversion specifier values in the POSIX locale.
Some conversion specifiers can be modified by the E and O
modifier characters to indicate a different format
or specification as specified in the LC_TIME locale description
(see the Base Definitions volume of
IEEE Std 1003.1-2001, Section 7.3.5, LC_TIME). If the
corresponding keyword (see era, era_year, era_d_fmt,
and alt_digits in the Base Definitions volume of
IEEE Std 1003.1-2001, Section 7.3.5, LC_TIME) is not specified or
not supported for the current locale, the unmodified conversion specifier
value shall be used.
Attempt to set the system date and time from the value given in the
operand. This is only possible if the user has appropriate
privileges and the system permits the setting of the system date and
time. The first mm is the month (number); dd is
the day (number); hh is the hour (number, 24-hour system); the
second mm is the minute (number); cc is the
century and is the first two digits of the year (this is optional);
yy is the last two digits of the year and is optional.
If century is not specified, then values in the range [69,99] shall
refer to years 1969 to 1999 inclusive, and values in the range
[00,68] shall refer to years 2000 to 2068 inclusive. The current year
is the default if yy is omitted.
The following environment variables shall affect the execution of
date:
When no formatting operand is specified, the output in the POSIX locale
shall be equivalent to specifying:
The standard error shall be used only for diagnostic messages.
The following exit values shall be returned:
Default.
The following sections are informative.
Conversion specifiers are of unspecified format when not in the POSIX
locale. Some of them can contain <newline>s in some
locales, so it may be difficult to use the format shown in standard
output for parsing the output of date in those
locales.
The range of values for %S extends from 0 to 60 seconds to accommodate
the occasional leap second.
Although certain of the conversion specifiers in the POSIX locale
(such as the name of the month) are shown with initial capital
letters, this need not be the case in other locales. Programs using
these fields may need to adjust the capitalization if the
output is going to be used at the beginning of a sentence.
The date string formatting capabilities are intended for use in Gregorian-style
calendars, possibly with a different starting
year (or years). The %x and %c conversion specifications,
however, are intended for local representation; these
may be based on a different, non-Gregorian calendar.
The %C conversion specification was introduced to allow a fallback
for the %EC (alternative year format base
year); it can be viewed as the base of the current subdivision in
the Gregorian calendar. The century number is calculated as the
year divided by 100 and truncated to an integer; it should not be
confused with the use of ordinal numbers for centuries (for
example, "twenty-first century".) Both the %Ey and %y
can then be viewed as the offset from %EC and
%C, respectively.
The E and O modifiers modify the traditional conversion
specifiers, so that they can always be used, even if
the implementation (or the current locale) does not support the modifier.
The E modifier supports alternative date formats, such as the
Japanese Emperor's Era, as long as these are based on the
Gregorian calendar system. Extending the E modifiers to other
date elements may provide an implementation-defined
extension capable of supporting other calendar systems, especially
in combination with the O modifier.
The O modifier supports time and date formats using the locale's
alternative numerical symbols, such as Kanji or Hindi
digits or ordinal number representation.
Non-European locales, whether they use Latin digits in computational
items or not, often have local forms of the digits for use
in date formats. This is not totally unknown even in Europe; a variant
of dates uses Roman numerals for the months: the third day
of September 1991 would be written as 3.IX.1991. In Japan, Kanji digits
are regularly used for dates; in Arabic-speaking countries,
Hindi digits are used. The %d, %e, %H, %I,
%m, %S, %U,
%w, %W, and %y conversion specifications always
return the date and time field in Latin digits (that
is, 0 to 9). The %O modifier was introduced to support the use
for display purposes of non-Latin digits. In the
LC_TIME category in localedef, the optional alt_digits
keyword is
intended for this purpose. As an example, assume the following (partial)
localedef
source:
With the above date, the command:
would yield 3.IX.1991. With the same d_fmt, but without the
alt_digits, the command would yield 3.9.1991.
Some of the new options for formatting are from the ISO C standard.
The -u option was introduced to allow portable
access to Coordinated Universal Time (UTC). The string "GMT0"
is allowed as an equivalent TZ value to be compatible
with all of the systems using the BSD implementation, where this option
originated.
The %e format conversion specification (adopted from System
V) was added because the ISO C standard conversion
specifications did not provide any way to produce the historical default
date output during the first nine days of any
month.
There are two varieties of day and week numbering supported (in addition
to any others created with the locale-dependent
%E and %O modifier characters):
OPTIONS
OPERANDS
Conversion Specifications
Modified Conversion Specifications
STDIN
INPUT FILES
ENVIRONMENT VARIABLES
ASYNCHRONOUS EVENTS
STDOUT
date "+%a %b %e %H:%M:%S %Z %Y"
STDERR
OUTPUT FILES
EXTENDED DESCRIPTION
EXIT STATUS
CONSEQUENCES OF ERRORS
APPLICATION USAGE
alt_digits "";"I";"II";"III";"IV";"V";"VI";"VII";"VIII" \
"IX";"X";"XI";"XII"
d_fmt "%e.%Om.%Y"
date "+%x"
EXAMPLES
$ date
Tue Jun 26 09:58:10 PDT 1990
$ date "+DATE: %m/%d/%y%nTIME: %H:%M:%S"
DATE: 11/02/91
TIME: 13:36:16
$ date "+TIME: %r"
TIME: 01:36:32 PM
$ LANG=da_DK.iso_8859-1 date
ons 02 okt 1991 15:03:32 CET
$ LANG=da_DK.iso_8859-1 \
date "+DATO: %A den %e. %B %Y%nKLOKKEN: %H:%M:%S"
DATO: onsdag den 2. oktober 1991
KLOKKEN: 15:03:56
$ LANG=De_DE.88591 date
Mi 02.Okt.1991, 15:01:21 MEZ
$ LANG=De_DE.88591 date "+DATUM: %A, %d. %B %Y%nZEIT: %H:%M:%S"
DATUM: Mittwoch, 02. Oktober 1991
ZEIT: 15:02:02
$ LANG=Fr_FR.88591 date
Mer 02 oct 1991 MET 15:03:32
$ LANG=Fr_FR.88591 date "+JOUR: %A %d %B %Y%nHEURE: %H:%M:%S"
JOUR: Mercredi 02 octobre 1991
HEURE: 15:03:56
RATIONALE
FUTURE DIRECTIONS
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .