1DATE(P) POSIX Programmer's Manual DATE(P)
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6 date - write the date and time
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9 date [-u] [+format]
10 date [-u] mmddhhmm[[cc]yy]
14
17 The date utility shall write the date and time to standard output or
18 attempt to set the system date and time. By default, the current date
19 and time shall be written. If an operand beginning with '+' is speci‐
20 fied, the output format of date shall be controlled by the conversion
21 specifications and other text in the operand.
22
24 The date utility shall conform to the Base Definitions volume of
25 IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
26 The following option shall be supported:
28 -u Perform operations as if the TZ environment variable was set to
30 the string "UTC0" , or its equivalent historical value of "GMT0"
31 . Otherwise, date shall use the timezone indicated by the TZ
32 environment variable or the system default if that variable is
33 unset or null.
34
37 The following operands shall be supported:
38 +format
40 When the format is specified, each conversion specifier shall be
41 replaced in the standard output by its corresponding value. All
42 other characters shall be copied to the output without change.
43 The output shall always be terminated with a <newline>.
44 Conversion Specifications
47 %a Locale's abbreviated weekday name.
48 %A Locale's full weekday name.
50 %b Locale's abbreviated month name.
52 %B Locale's full month name.
54 %c Locale's appropriate date and time representation.
56 %C Century (a year divided by 100 and truncated to an integer) as a
58 decimal number [00,99].
59 %d Day of the month as a decimal number [01,31].
61 %D Date in the format mm/dd/yy.
63 %e Day of the month as a decimal number [1,31] in a two-digit field
65 with leading space character fill.
66 %h A synonym for %b .
68 %H Hour (24-hour clock) as a decimal number [00,23].
70 %I Hour (12-hour clock) as a decimal number [01,12].
72 %j Day of the year as a decimal number [001,366].
74 %m Month as a decimal number [01,12].
76 %M Minute as a decimal number [00,59].
78 %n A <newline>.
80 %p Locale's equivalent of either AM or PM.
82 %r 12-hour clock time [01,12] using the AM/PM notation; in the
84 POSIX locale, this shall be equivalent to %I : %M : %S %p .
85 %S Seconds as a decimal number [00,60].
87 %t A <tab>.
89 %T 24-hour clock time [00,23] in the format HH:MM:SS.
91 %u Weekday as a decimal number [1,7] (1=Monday).
93 %U Week of the year (Sunday as the first day of the week) as a dec‐
95 imal number [00,53]. All days in a new year preceding the first
96 Sunday shall be considered to be in week 0.
97 %V Week of the year (Monday as the first day of the week) as a dec‐
99 imal number [01,53]. If the week containing January 1 has four
100 or more days in the new year, then it shall be considered week
101 1; otherwise, it shall be the last week of the previous year,
102 and the next week shall be week 1.
103 %w Weekday as a decimal number [0,6] (0=Sunday).
105 %W Week of the year (Monday as the first day of the week) as a dec‐
107 imal number [00,53]. All days in a new year preceding the first
108 Monday shall be considered to be in week 0.
109 %x Locale's appropriate date representation.
111 %X Locale's appropriate time representation.
113 %y Year within century [00,99].
115 %Y Year with century as a decimal number.
117 %Z Timezone name, or no characters if no timezone is determinable.
119 %% A percent sign character.
121 See the Base Definitions volume of IEEE Std 1003.1-2001, Section 7.3.5,
124 LC_TIME for the conversion specifier values in the POSIX locale.
125 Modified Conversion Specifications
127 Some conversion specifiers can be modified by the E and O modifier
128 characters to indicate a different format or specification as specified
129 in the LC_TIME locale description (see the Base Definitions volume of
130 IEEE Std 1003.1-2001, Section 7.3.5, LC_TIME). If the corresponding
131 keyword (see era, era_year, era_d_fmt, and alt_digits in the Base Defi‐
132 nitions volume of IEEE Std 1003.1-2001, Section 7.3.5, LC_TIME) is not
133 specified or not supported for the current locale, the unmodified con‐
134 version specifier value shall be used.
135 %Ec Locale's alternative appropriate date and time representation.
137 %EC The name of the base year (period) in the locale's alternative
139 representation.
140 %Ex Locale's alternative date representation.
142 %EX Locale's alternative time representation.
144 %Ey Offset from %EC (year only) in the locale's alternative repre‐
146 sentation.
147 %EY Full alternative year representation.
149 %Od Day of month using the locale's alternative numeric symbols.
151 %Oe Day of month using the locale's alternative numeric symbols.
153 %OH Hour (24-hour clock) using the locale's alternative numeric sym‐
155 bols.
156 %OI Hour (12-hour clock) using the locale's alternative numeric sym‐
158 bols.
159 %Om Month using the locale's alternative numeric symbols.
161 %OM Minutes using the locale's alternative numeric symbols.
163 %OS Seconds using the locale's alternative numeric symbols.
165 %Ou Weekday as a number in the locale's alternative representation
167 (Monday = 1).
168 %OU Week number of the year (Sunday as the first day of the week)
170 using the locale's alternative numeric symbols.
171 %OV Week number of the year (Monday as the first day of the week,
173 rules corresponding to %V ), using the locale's alternative
174 numeric symbols.
175 %Ow Weekday as a number in the locale's alternative representation
177 (Sunday = 0).
178 %OW Week number of the year (Monday as the first day of the week)
180 using the locale's alternative numeric symbols.
181 %Oy Year (offset from %C ) in alternative representation.
183 mmddhhmm[[cc]yy]
187 Attempt to set the system date and time from the value given in
189 the operand. This is only possible if the user has appropriate
190 privileges and the system permits the setting of the system date
191 and time. The first mm is the month (number); dd is the day
192 (number); hh is the hour (number, 24-hour system); the second mm
193 is the minute (number); cc is the century and is the first two
194 digits of the year (this is optional); yy is the last two digits
195 of the year and is optional. If century is not specified, then
196 values in the range [69,99] shall refer to years 1969 to 1999
197 inclusive, and values in the range [00,68] shall refer to years
198 2000 to 2068 inclusive. The current year is the default if yy is
199 omitted.
200 Note:
202 It is expected that in a future version of IEEE Std 1003.1-2001
203 the default century inferred from a 2-digit year will change.
204 (This would apply to all commands accepting a 2-digit year as
205 input.)
206
210 Not used.
211
213 None.
214
216 The following environment variables shall affect the execution of date:
217 LANG Provide a default value for the internationalization variables
219 that are unset or null. (See the Base Definitions volume of
220 IEEE Std 1003.1-2001, Section 8.2, Internationalization Vari‐
221 ables for the precedence of internationalization variables used
222 to determine the values of locale categories.)
223 LC_ALL If set to a non-empty string value, override the values of all
225 the other internationalization variables.
226 LC_CTYPE
228 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 error.
235 LC_TIME
237 Determine the format and contents of date and time strings writ‐
238 ten by date.
239 NLSPATH
241 Determine the location of message catalogs for the processing of
242 LC_MESSAGES .
243 TZ Determine the timezone in which the time and date are written,
245 unless the -u option is specified. If the TZ variable is unset
246 or null and -u is not specified, an unspecified system default
247 timezone is used.
248
251 Default.
252
254 When no formatting operand is specified, the output in the POSIX locale
255 shall be equivalent to specifying:
256 date "+%a %b %e %H:%M:%S %Z %Y"
259
261 The standard error shall be used only for diagnostic messages.
262
264 None.
265
267 None.
268
270 The following exit values shall be returned:
271 0 The date was written successfully.
273 >0 An error occurred.
275
278 Default.
279 The following sections are informative.
281
283 Conversion specifiers are of unspecified format when not in the POSIX
284 locale. Some of them can contain <newline>s in some locales, so it may
285 be difficult to use the format shown in standard output for parsing the
286 output of date in those locales.
287 The range of values for %S extends from 0 to 60 seconds to accommodate
289 the occasional leap second.
290 Although certain of the conversion specifiers in the POSIX locale (such
292 as the name of the month) are shown with initial capital letters, this
293 need not be the case in other locales. Programs using these fields may
294 need to adjust the capitalization if the output is going to be used at
295 the beginning of a sentence.
296 The date string formatting capabilities are intended for use in Grego‐
298 rian-style calendars, possibly with a different starting year (or
299 years). The %x and %c conversion specifications, however, are intended
300 for local representation; these may be based on a different, non-Grego‐
301 rian calendar.
302 The %C conversion specification was introduced to allow a fallback for
304 the %EC (alternative year format base year); it can be viewed as the
305 base of the current subdivision in the Gregorian calendar. The century
306 number is calculated as the year divided by 100 and truncated to an
307 integer; it should not be confused with the use of ordinal numbers for
308 centuries (for example, "twenty-first century".) Both the %Ey and %y
309 can then be viewed as the offset from %EC and %C , respectively.
310 The E and O modifiers modify the traditional conversion specifiers, so
312 that they can always be used, even if the implementation (or the cur‐
313 rent locale) does not support the modifier.
314 The E modifier supports alternative date formats, such as the Japanese
316 Emperor's Era, as long as these are based on the Gregorian calendar
317 system. Extending the E modifiers to other date elements may provide an
318 implementation-defined extension capable of supporting other calendar
319 systems, especially in combination with the O modifier.
320 The O modifier supports time and date formats using the locale's alter‐
322 native numerical symbols, such as Kanji or Hindi digits or ordinal num‐
323 ber representation.
324 Non-European locales, whether they use Latin digits in computational
326 items or not, often have local forms of the digits for use in date for‐
327 mats. This is not totally unknown even in Europe; a variant of dates
328 uses Roman numerals for the months: the third day of September 1991
329 would be written as 3.IX.1991. In Japan, Kanji digits are regularly
330 used for dates; in Arabic-speaking countries, Hindi digits are used.
331 The %d , %e , %H , %I , %m , %S , %U , %w , %W , and %y conversion
332 specifications always return the date and time field in Latin digits
333 (that is, 0 to 9). The %O modifier was introduced to support the use
334 for display purposes of non-Latin digits. In the LC_TIME category in
335 localedef, the optional alt_digits keyword is intended for this pur‐
336 pose. As an example, assume the following (partial) localedef source:
337 alt_digits "";"I";"II";"III";"IV";"V";"VI";"VII";"VIII" \
340 "IX";"X";"XI";"XII"
341 d_fmt "%e.%Om.%Y"
342 With the above date, the command:
344 date "+%x"
347 would yield 3.IX.1991. With the same d_fmt, but without the alt_digits,
349 the command would yield 3.9.1991.
350
352 1. The following are input/output examples of date used at arbitrary
353 times in the POSIX locale:
354 $ date
357 Tue Jun 26 09:58:10 PDT 1990
358 $ date "+DATE: %m/%d/%y%nTIME: %H:%M:%S"
361 DATE: 11/02/91
362 TIME: 13:36:16
363 $ date "+TIME: %r"
366 TIME: 01:36:32 PM
367 2. Examples for Denmark, where the default date and time format is %a
369 %d %b %Y %T %Z :
370 $ LANG=da_DK.iso_8859-1 date
373 ons 02 okt 1991 15:03:32 CET
374 $ LANG=da_DK.iso_8859-1 \
377 date "+DATO: %A den %e. %B %Y%nKLOKKEN: %H:%M:%S"
378 DATO: onsdag den 2. oktober 1991
379 KLOKKEN: 15:03:56
380 3. Examples for Germany, where the default date and time format is %a
382 %d . %h . %Y , %T %Z :
383 $ LANG=De_DE.88591 date
386 Mi 02.Okt.1991, 15:01:21 MEZ
387 $ LANG=De_DE.88591 date "+DATUM: %A, %d. %B %Y%nZEIT: %H:%M:%S"
390 DATUM: Mittwoch, 02. Oktober 1991
391 ZEIT: 15:02:02
392 4. Examples for France, where the default date and time format is %a
394 %d %h %Y %Z %T :
395 $ LANG=Fr_FR.88591 date
398 Mer 02 oct 1991 MET 15:03:32
399 $ LANG=Fr_FR.88591 date "+JOUR: %A %d %B %Y%nHEURE: %H:%M:%S"
402 JOUR: Mercredi 02 octobre 1991
403 HEURE: 15:03:56
404
406 Some of the new options for formatting are from the ISO C standard.
407 The -u option was introduced to allow portable access to Coordinated
408 Universal Time (UTC). The string "GMT0" is allowed as an equivalent TZ
409 value to be compatible with all of the systems using the BSD implemen‐
410 tation, where this option originated.
411 The %e format conversion specification (adopted from System V) was
413 added because the ISO C standard conversion specifications did not pro‐
414 vide any way to produce the historical default date output during the
415 first nine days of any month.
416 There are two varieties of day and week numbering supported (in addi‐
418 tion to any others created with the locale-dependent %E and %O modifier
419 characters):
420 * The historical variety in which Sunday is the first day of the week
422 and the weekdays preceding the first Sunday of the year are consid‐
423 ered week 0. These are represented by %w and %U . A variant of this
424 is %W , using Monday as the first day of the week, but still refer‐
425 ring to week 0. This view of the calendar was retained because so
426 many historical applications depend on it and the ISO C standard
427 strftime() function, on which many date implementations are based,
428 was defined in this way.
429 * The international standard, based on the ISO 8601:2000 standard
431 where Monday is the first weekday and the algorithm for the first
432 week number is more complex: If the week (Monday to Sunday) contain‐
433 ing January 1 has four or more days in the new year, then it is week
434 1; otherwise, it is week 53 of the previous year, and the next week
435 is week 1. These are represented by the new conversion specifica‐
436 tions %u and %V , added as a result of international comments.
437
439 None.
440
442 The System Interfaces volume of IEEE Std 1003.1-2001, printf(), strf‐
443 time()
444
446 Portions of this text are reprinted and reproduced in electronic form
447 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
448 -- Portable Operating System Interface (POSIX), The Open Group Base
449 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
450 Electrical and Electronics Engineers, Inc and The Open Group. In the
451 event of any discrepancy between this version and the original IEEE and
452 The Open Group Standard, the original IEEE and The Open Group Standard
453 is the referee document. The original Standard can be obtained online
454 at http://www.opengroup.org/unix/online.html .
455IEEE/The Open Group 2003 DATE(P)