PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

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

PROLOG         top

       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         top

       date — write the date and time

SYNOPSIS         top

       date [−u] [+format]

       date [−u] mmddhhmm[[cc]yy]

DESCRIPTION         top

       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 output format of date shall be controlled by the
       conversion specifications and other text in the operand.

OPTIONS         top

       The date utility shall conform to the Base Definitions volume of
       POSIX.1‐2008, 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         top

       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
                         containing 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 POSIX.1‐2008, 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 POSIX.1‐2008, 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 POSIX.1‐2008, 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 this
                           standard 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         top

       Not used.

INPUT FILES         top

       None.

ENVIRONMENT VARIABLES         top

       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 POSIX.1‐2008, Section 8.2, Internationalization
                 Variables for the precedence 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 example, 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 written 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         top

       Default.

STDOUT         top

       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         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top

       None.

EXTENDED DESCRIPTION         top

       None.

EXIT STATUS         top

       The following exit values shall be returned:

        0    The date was written successfully.

       >0    An error occurred.

CONSEQUENCES OF ERRORS         top

       Default.

       The following sections are informative.

APPLICATION USAGE         top

       Conversion specifiers are of unspecified format when not in the POSIX
       locale. Some of them can contain <newline> characters 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:

           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         top

        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         top

       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 8601:2004 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         top

       None.

SEE ALSO         top

       The Base Definitions volume of POSIX.1‐2008, Section 7.3.5, LC_TIME,
       Chapter 8, Environment Variables, Section 12.2, Utility Syntax
       Guidelines

       The System Interfaces volume of POSIX.1‐2008, fprintf(3p),
       strftime(3p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the
       source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                 2013                            DATE(1P)