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DATE(1P)                   POSIX Programmer's Manual                  DATE(1P)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may dif-
       fer (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]



       date [-u] mmddhhmm[[cc]yy]


DESCRIPTION
       The  date utility shall write the date and time to standard output  or attempt to set the system date and time.
       By default, the current date and time shall be written. If an operand beginning with '+' is specified, the out-
       put format of date shall be controlled by the conversion specifications and other text in the operand.

OPTIONS
       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:

       -u     Perform operations as if the TZ environment variable was set to the string  "UTC0",  or  its  equivalent
              historical  value  of  "GMT0"  .  Otherwise, date shall use the timezone indicated by the TZ environment
              variable or the system default if that variable is unset or null.


OPERANDS
       The following operands shall be supported:

       +format
              When the format is specified, each conversion specifier shall be replaced in the standard output by  its
              corresponding  value.   All  other  characters shall be copied to the output without change.  The output
              shall always be terminated with a <newline>.


   Conversion Specifications
       %a     Locale's abbreviated weekday name.

       %A     Locale's full weekday name.

       %b     Locale's abbreviated month name.

       %B     Locale's full month name.

       %c     Locale's appropriate date and time representation.

       %C     Century (a year divided by 100 and truncated to an integer) as a decimal number [00,99].

       %d     Day of the month as a decimal number [01,31].

       %D     Date in the format mm/dd/yy.

       %e     Day of the month as a decimal number [1,31] in a two-digit field with leading space character fill.

       %h     A synonym for %b .

       %H     Hour (24-hour clock) as a decimal number [00,23].

       %I     Hour (12-hour clock) as a decimal number [01,12].

       %j     Day of the year as a decimal number [001,366].

       %m     Month as a decimal number [01,12].

       %M     Minute as a decimal number [00,59].

       %n     A <newline>.

       %p     Locale's equivalent of either AM or PM.

       %r     12-hour clock time [01,12] using the AM/PM notation; in the POSIX locale, this shall be equivalent to %I
              : %M : %S %p .

       %S     Seconds as a decimal number [00,60].

       %t     A <tab>.

       %T     24-hour clock time [00,23] in the format HH:MM:SS.

       %u     Weekday as a decimal number [1,7] (1=Monday).

       %U     Week  of  the  year (Sunday as the first day of the week) as a decimal number [00,53]. All days in a new
              year preceding the first Sunday shall be considered to be in week 0.

       %V     Week of the year (Monday as the first day of the week) as a decimal number [01,53]. If the week contain-
              ing  January  1 has four or more days in the new year, then it shall be considered week 1; otherwise, it
              shall be the last week of the previous year, and the next week shall be week 1.

       %w     Weekday as a decimal number [0,6] (0=Sunday).

       %W     Week of the year (Monday as the first day of the week) as a decimal number [00,53]. All days  in  a  new
              year preceding the first Monday shall be considered to be in week 0.

       %x     Locale's appropriate date representation.

       %X     Locale's appropriate time representation.

       %y     Year within century [00,99].

       %Y     Year with century as a decimal number.

       %Z     Timezone name, or no characters if no timezone is determinable.

       %%     A percent sign character.


       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.

   Modified Conversion Specifications
       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.

       %Ec    Locale's alternative appropriate date and time representation.

       %EC    The name of the base year (period) in the locale's alternative representation.

       %Ex    Locale's alternative date representation.

       %EX    Locale's alternative time representation.

       %Ey    Offset from %EC (year only) in the locale's alternative representation.

       %EY    Full alternative year representation.

       %Od    Day of month using the locale's alternative numeric symbols.

       %Oe    Day of month using the locale's alternative numeric symbols.

       %OH    Hour (24-hour clock) using the locale's alternative numeric symbols.

       %OI    Hour (12-hour clock) using the locale's alternative numeric symbols.

       %Om    Month using the locale's alternative numeric symbols.

       %OM    Minutes using the locale's alternative numeric symbols.

       %OS    Seconds using the locale's alternative numeric symbols.

       %Ou    Weekday as a number in the locale's alternative representation (Monday = 1).

       %OU    Week number of the year (Sunday as the first day of the week) using  the  locale's  alternative  numeric
              symbols.

       %OV    Week  number  of  the  year (Monday as the first day of the week, rules corresponding to %V ), using the
              locale's alternative numeric symbols.

       %Ow    Weekday as a number in the locale's alternative representation (Sunday = 0).

       %OW    Week number of the year (Monday as the first day of the week) using  the  locale's  alternative  numeric
              symbols.

       %Oy    Year (offset from %C ) in alternative representation.



       mmddhhmm[[cc]yy]

              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.

       Note:
              It  is  expected  that  in  a future version of IEEE Std 1003.1-2001 the default century inferred from a
              2-digit year will change. (This would apply to all commands accepting a 2-digit year as input.)



STDIN
       Not used.

INPUT FILES
       None.

ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of date:

       LANG   Provide a default value for the internationalization variables that are unset or  null.  (See  the  Base
              Definitions  volume  of IEEE Std 1003.1-2001, Section 8.2, Internationalization Variables for the prece-
              dence of internationalization variables used to determine the values of locale categories.)

       LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables.

       LC_CTYPE
              Determine  the locale for the interpretation of sequences of bytes of text data as characters (for exam-
              ple, single-byte as opposed to multi-byte characters in arguments).

       LC_MESSAGES
              Determine the locale that should be used to affect the format and contents of diagnostic messages  writ-
              ten to standard error.

       LC_TIME
              Determine the format and contents of date and time strings written by date.

       NLSPATH
              Determine the location of message catalogs for the processing of LC_MESSAGES .

       TZ     Determine the timezone in which the time and date are written, unless the -u option is specified. If the
              TZ variable is unset or null and -u is not specified, an unspecified system default timezone is used.


ASYNCHRONOUS EVENTS
       Default.

STDOUT
       When no formatting operand is specified, the output in the POSIX locale shall be equivalent to specifying:


              date "+%a %b %e %H:%M:%S %Z %Y"

STDERR
       The standard error shall be used only for diagnostic messages.

OUTPUT FILES
       None.

EXTENDED DESCRIPTION
       None.

EXIT STATUS
       The following exit values shall be returned:

        0     The date was written successfully.

       >0     An error occurred.


CONSEQUENCES OF ERRORS
       Default.

       The following sections are informative.

APPLICATION USAGE
       Conversion specifiers are of unspecified format when not in the POSIX locale. Some of them  can  contain  <new-
       line>s  in some locales, so it may be difficult to use the format shown in standard output for parsing the out-
       put 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 dif-
       ferent  starting year (or years). The %x and %c conversion specifications, however, are intended for local rep-
       resentation; 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  imple-
       mentation-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:


              alt_digits  "";"I";"II";"III";"IV";"V";"VI";"VII";"VIII" \
                          "IX";"X";"XI";"XII"
              d_fmt       "%e.%Om.%Y"

       With the above date, the command:


              date "+%x"

       would yield 3.IX.1991. With the same d_fmt, but without the alt_digits, the command would yield 3.9.1991.

EXAMPLES
        1. The following are input/output examples of date used at arbitrary times in the POSIX locale:


           $ 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


        2. Examples for Denmark, where the default date and time format is %a %d %b %Y %T %Z :


           $ 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


        3. Examples for Germany, where the default date and time format is %a %d . %h . %Y, %T %Z :


           $ 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


        4. Examples for France, where the default date and time format is %a %d %h %Y %Z %T :


           $ 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
       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):

        * The  historical  variety  in  which Sunday is the first day of the week and the weekdays preceding the first
          Sunday of the year are considered week 0. These are represented by %w and %U . A  variant  of  this  is  %W,
          using  Monday  as  the  first  day of the week, but still referring to week 0. This view of the calendar was
          retained because so many historical applications depend on it and the ISO C standard strftime() function, on
          which many date implementations are based, was defined in this way.


        * The  international  standard,  based on the ISO 8601:2000 standard where Monday is the first weekday and the
          algorithm for the first week number is more complex: If the week (Monday to Sunday) containing January 1 has
          four or more days in the new year, then it is week 1; otherwise, it is week 53 of the previous year, and the
          next week is week 1. These are represented by the new conversion specifications %u and %V, added as a result
          of international comments.


FUTURE DIRECTIONS
       None.

SEE ALSO
       The System Interfaces volume of IEEE Std 1003.1-2001, printf(), strftime()

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Stan-
       dard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base  Specifica-
       tions  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 Stan-
       dard,  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 .



IEEE/The Open Group                  2003                             DATE(1P)