1DATE(1P) POSIX Programmer's Manual DATE(1P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
13 date — write the date and time
14
16 date [−u] [+format]
17 date [−u] mmddhhmm[[cc]yy]
19
21 The date utility shall write the date and time to standard output or
22 attempt to set the system date and time. By default, the current date
23 and time shall be written. If an operand beginning with '+' is speci‐
24 fied, the output format of date shall be controlled by the conversion
25 specifications and other text in the operand.
26
28 The date utility shall conform to the Base Definitions volume of
29 POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines.
30 The following option shall be supported:
32 −u Perform operations as if the TZ environment variable was set
34 to the string "UTC0", or its equivalent historical value of
35 "GMT0". Otherwise, date shall use the timezone indicated by
36 the TZ environment variable or the system default if that
37 variable is unset or null.
38
40 The following operands shall be supported:
41 +format When the format is specified, each conversion specifier shall
43 be replaced in the standard output by its corresponding
44 value. All other characters shall be copied to the output
45 without change. The output shall always be terminated with a
46 <newline>.
47 Conversion Specifications
49 %a Locale's abbreviated weekday name.
50 %A Locale's full weekday name.
52 %b Locale's abbreviated month name.
54 %B Locale's full month name.
56 %c Locale's appropriate date and time representation.
58 %C Century (a year divided by 100 and truncated to an
60 integer) as a decimal number [00,99].
61 %d Day of the month as a decimal number [01,31].
63 %D Date in the format mm/dd/yy.
65 %e Day of the month as a decimal number [1,31] in a two-
67 digit field with leading <space> character fill.
68 %h A synonym for %b.
70 %H Hour (24-hour clock) as a decimal number [00,23].
72 %I Hour (12-hour clock) as a decimal number [01,12].
74 %j Day of the year as a decimal number [001,366].
76 %m Month as a decimal number [01,12].
78 %M Minute as a decimal number [00,59].
80 %n A <newline>.
82 %p Locale's equivalent of either AM or PM.
84 %r 12-hour clock time [01,12] using the AM/PM notation;
86 in the POSIX locale, this shall be equivalent to
87 %I:%M:%S %p.
88 %S Seconds as a decimal number [00,60].
90 %t A <tab>.
92 %T 24-hour clock time [00,23] in the format HH:MM:SS.
94 %u Weekday as a decimal number [1,7] (1=Monday).
96 %U Week of the year (Sunday as the first day of the
98 week) as a decimal number [00,53]. All days in a new
99 year preceding the first Sunday shall be considered
100 to be in week 0.
101 %V Week of the year (Monday as the first day of the
103 week) as a decimal number [01,53]. If the week con‐
104 taining January 1 has four or more days in the new
105 year, then it shall be considered week 1; otherwise,
106 it shall be the last week of the previous year, and
107 the next week shall be week 1.
108 %w Weekday as a decimal number [0,6] (0=Sunday).
110 %W Week of the year (Monday as the first day of the
112 week) as a decimal number [00,53]. All days in a new
113 year preceding the first Monday shall be considered
114 to be in week 0.
115 %x Locale's appropriate date representation.
117 %X Locale's appropriate time representation.
119 %y Year within century [00,99].
121 %Y Year with century as a decimal number.
123 %Z Timezone name, or no characters if no timezone is
125 determinable.
126 %% A <percent-sign> character.
128 See the Base Definitions volume of POSIX.1‐2008, Section
130 7.3.5, LC_TIME for the conversion specifier values in the
131 POSIX locale.
132 Modified Conversion Specifications
134 Some conversion specifiers can be modified by the E and O modifier
135 characters to indicate a different format or specification as specified
136 in the LC_TIME locale description (see the Base Definitions volume of
137 POSIX.1‐2008, Section 7.3.5, LC_TIME). If the corresponding keyword
138 (see era, era_year, era_d_fmt, and alt_digits in the Base Definitions
139 volume of POSIX.1‐2008, Section 7.3.5, LC_TIME) is not specified or not
140 supported for the current locale, the unmodified conversion specifier
141 value shall be used.
142 %Ec Locale's alternative appropriate date and time representation.
144 %EC The name of the base year (period) in the locale's alternative
146 representation.
147 %Ex Locale's alternative date representation.
149 %EX Locale's alternative time representation.
151 %Ey Offset from %EC (year only) in the locale's alternative repre‐
153 sentation.
154 %EY Full alternative year representation.
156 %Od Day of month using the locale's alternative numeric symbols.
158 %Oe Day of month using the locale's alternative numeric symbols.
160 %OH Hour (24-hour clock) using the locale's alternative numeric
162 symbols.
163 %OI Hour (12-hour clock) using the locale's alternative numeric
165 symbols.
166 %Om Month using the locale's alternative numeric symbols.
168 %OM Minutes using the locale's alternative numeric symbols.
170 %OS Seconds using the locale's alternative numeric symbols.
172 %Ou Weekday as a number in the locale's alternative representation
174 (Monday = 1).
175 %OU Week number of the year (Sunday as the first day of the week)
177 using the locale's alternative numeric symbols.
178 %OV Week number of the year (Monday as the first day of the week,
180 rules corresponding to %V), using the locale's alternative
181 numeric symbols.
182 %Ow Weekday as a number in the locale's alternative representation
184 (Sunday = 0).
185 %OW Week number of the year (Monday as the first day of the week)
187 using the locale's alternative numeric symbols.
188 %Oy Year (offset from %C) in alternative representation.
190 mmddhhmm[[cc]yy]
192 Attempt to set the system date and time from the value given
193 in the operand. This is only possible if the user has appro‐
194 priate privileges and the system permits the setting of the
195 system date and time. The first mm is the month (number); dd
196 is the day (number); hh is the hour (number, 24-hour system);
197 the second mm is the minute (number); cc is the century and
198 is the first two digits of the year (this is optional); yy is
199 the last two digits of the year and is optional. If century
200 is not specified, then values in the range [69,99] shall
201 refer to years 1969 to 1999 inclusive, and values in the
202 range [00,68] shall refer to years 2000 to 2068 inclusive.
203 The current year is the default if yy is omitted.
204 Note: It is expected that in a future version of this
206 standard the default century inferred from a
207 2-digit year will change. (This would apply to all
208 commands accepting a 2-digit year as input.)
209
211 Not used.
212
214 None.
215
217 The following environment variables shall affect the execution of date:
218 LANG Provide a default value for the internationalization vari‐
220 ables that are unset or null. (See the Base Definitions vol‐
221 ume of POSIX.1‐2008, Section 8.2, Internationalization Vari‐
222 ables for the precedence of internationalization variables
223 used to determine the values of locale categories.)
224 LC_ALL If set to a non-empty string value, override the values of
226 all the other internationalization variables.
227 LC_CTYPE Determine the locale for the interpretation of sequences of
229 bytes of text data as characters (for example, single-byte as
230 opposed to multi-byte characters in arguments).
231 LC_MESSAGES
233 Determine the locale that should be used to affect the format
234 and contents of diagnostic messages written to standard
235 error.
236 LC_TIME Determine the format and contents of date and time strings
238 written by date.
239 NLSPATH Determine the location of message catalogs for the processing
241 of LC_MESSAGES.
242 TZ Determine the timezone in which the time and date are writ‐
244 ten, unless the −u option is specified. If the TZ variable is
245 unset or null and −u is not specified, an unspecified system
246 default timezone is used.
247
249 Default.
250
252 When no formatting operand is specified, the output in the POSIX locale
253 shall be equivalent to specifying:
254 date "+%a %b %e %H:%M:%S %Z %Y"
256
258 The standard error shall be used only for diagnostic messages.
259
261 None.
262
264 None.
265
267 The following exit values shall be returned:
268 0 The date was written successfully.
270 >0 An error occurred.
272
274 Default.
275 The following sections are informative.
277
279 Conversion specifiers are of unspecified format when not in the POSIX
280 locale. Some of them can contain <newline> characters in some locales,
281 so it may be difficult to use the format shown in standard output for
282 parsing the output of date in those locales.
283 The range of values for %S extends from 0 to 60 seconds to accommodate
285 the occasional leap second.
286 Although certain of the conversion specifiers in the POSIX locale (such
288 as the name of the month) are shown with initial capital letters, this
289 need not be the case in other locales. Programs using these fields may
290 need to adjust the capitalization if the output is going to be used at
291 the beginning of a sentence.
292 The date string formatting capabilities are intended for use in Grego‐
294 rian-style calendars, possibly with a different starting year (or
295 years). The %x and %c conversion specifications, however, are intended
296 for local representation; these may be based on a different, non-Grego‐
297 rian calendar.
298 The %C conversion specification was introduced to allow a fallback for
300 the %EC (alternative year format base year); it can be viewed as the
301 base of the current subdivision in the Gregorian calendar. The century
302 number is calculated as the year divided by 100 and truncated to an
303 integer; it should not be confused with the use of ordinal numbers for
304 centuries (for example, ``twenty-first century''.) Both the %Ey and %y
305 can then be viewed as the offset from %EC and %C, respectively.
306 The E and O modifiers modify the traditional conversion specifiers, so
308 that they can always be used, even if the implementation (or the cur‐
309 rent locale) does not support the modifier.
310 The E modifier supports alternative date formats, such as the Japanese
312 Emperor's Era, as long as these are based on the Gregorian calendar
313 system. Extending the E modifiers to other date elements may provide an
314 implementation-defined extension capable of supporting other calendar
315 systems, especially in combination with the O modifier.
316 The O modifier supports time and date formats using the locale's alter‐
318 native numerical symbols, such as Kanji or Hindi digits or ordinal num‐
319 ber representation.
320 Non-European locales, whether they use Latin digits in computational
322 items or not, often have local forms of the digits for use in date for‐
323 mats. This is not totally unknown even in Europe; a variant of dates
324 uses Roman numerals for the months: the third day of September 1991
325 would be written as 3.IX.1991. In Japan, Kanji digits are regularly
326 used for dates; in Arabic-speaking countries, Hindi digits are used.
327 The %d, %e, %H, %I, %m, %S, %U, %w, %W, and %y conversion specifica‐
328 tions always return the date and time field in Latin digits (that is, 0
329 to 9). The %O modifier was introduced to support the use for display
330 purposes of non-Latin digits. In the LC_TIME category in localedef, the
331 optional alt_digits keyword is intended for this purpose. As an exam‐
332 ple, assume the following (partial) localedef source:
333 alt_digits "";"I";"II";"III";"IV";"V";"VI";"VII";"VIII" \
335 "IX";"X";"XI";"XII"
336 d_fmt "%e.%Om.%Y"
337 With the above date, the command:
339 date "+%x"
341 would yield 3.IX.1991. With the same d_fmt, but without the alt_digits,
343 the command would yield 3.9.1991.
344
346 1. The following are input/output examples of date used at arbitrary
347 times in the POSIX locale:
348 $ date
350 Tue Jun 26 09:58:10 PDT 1990
351 $ date "+DATE: %m/%d/%y%nTIME: %H:%M:%S"
353 DATE: 11/02/91
354 TIME: 13:36:16
355 $ date "+TIME: %r"
357 TIME: 01:36:32 PM
358 2. Examples for Denmark, where the default date and time format is %a
360 %d %b %Y %T %Z:
361 $ LANG=da_DK.iso_8859−1 date
363 ons 02 okt 1991 15:03:32 CET
364 $ LANG=da_DK.iso_8859−1 \
366 date "+DATO: %A den %e. %B %Y%nKLOKKEN: %H:%M:%S"
367 DATO: onsdag den 2. oktober 1991
368 KLOKKEN: 15:03:56
369 3. Examples for Germany, where the default date and time format is %a
371 %d.%h.%Y, %T %Z:
372 $ LANG=De_DE.88591 date
374 Mi 02.Okt.1991, 15:01:21 MEZ
375 $ LANG=De_DE.88591 date "+DATUM: %A, %d. %B %Y%nZEIT: %H:%M:%S"
377 DATUM: Mittwoch, 02. Oktober 1991
378 ZEIT: 15:02:02
379 4. Examples for France, where the default date and time format is %a
381 %d %h %Y %Z %T:
382 $ LANG=Fr_FR.88591 date
384 Mer 02 oct 1991 MET 15:03:32
385 $ LANG=Fr_FR.88591 date "+JOUR: %A %d %B %Y%nHEURE: %H:%M:%S"
387 JOUR: Mercredi 02 octobre 1991
388 HEURE: 15:03:56
389
391 Some of the new options for formatting are from the ISO C standard. The
392 −u option was introduced to allow portable access to Coordinated Uni‐
393 versal Time (UTC). The string "GMT0" is allowed as an equivalent TZ
394 value to be compatible with all of the systems using the BSD implemen‐
395 tation, where this option originated.
396 The %e format conversion specification (adopted from System V) was
398 added because the ISO C standard conversion specifications did not pro‐
399 vide any way to produce the historical default date output during the
400 first nine days of any month.
401 There are two varieties of day and week numbering supported (in addi‐
403 tion to any others created with the locale-dependent %E and %O modifier
404 characters):
405 * The historical variety in which Sunday is the first day of the week
407 and the weekdays preceding the first Sunday of the year are consid‐
408 ered week 0. These are represented by %w and %U. A variant of this
409 is %W, using Monday as the first day of the week, but still refer‐
410 ring to week 0. This view of the calendar was retained because so
411 many historical applications depend on it and the ISO C standard
412 strftime() function, on which many date implementations are based,
413 was defined in this way.
414 * The international standard, based on the ISO 8601:2004 standard
416 where Monday is the first weekday and the algorithm for the first
417 week number is more complex: If the week (Monday to Sunday) con‐
418 taining January 1 has four or more days in the new year, then it is
419 week 1; otherwise, it is week 53 of the previous year, and the next
420 week is week 1. These are represented by the new conversion speci‐
421 fications %u and %V, added as a result of international comments.
422
424 None.
425
427 The Base Definitions volume of POSIX.1‐2008, Section 7.3.5, LC_TIME,
428 Chapter 8, Environment Variables, Section 12.2, Utility Syntax Guide‐
429 lines
430 The System Interfaces volume of POSIX.1‐2008, fprintf(), strftime()
432
434 Portions of this text are reprinted and reproduced in electronic form
435 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
436 -- Portable Operating System Interface (POSIX), The Open Group Base
437 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
438 cal and Electronics Engineers, Inc and The Open Group. (This is
439 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
440 event of any discrepancy between this version and the original IEEE and
441 The Open Group Standard, the original IEEE and The Open Group Standard
442 is the referee document. The original Standard can be obtained online
443 at http://www.unix.org/online.html .
444 Any typographical or formatting errors that appear in this page are
446 most likely to have been introduced during the conversion of the source
447 files to man page format. To report such errors, see https://www.ker‐
448 nel.org/doc/man-pages/reporting_bugs.html .
449IEEE/The Open Group 2013 DATE(1P)