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31 .\" @(#)date.1 8.3 (Berkeley) 4/28/95
32 .\" $FreeBSD: src/bin/date/date.1,v 1.72 2005/02/13 22:25:09 ru Exp $
39 .Nd display or set date and time
52 .Op Cm + Ns Ar output_fmt
56 .Op Oo Oo Oo Oo Ar cc Oc Ar yy Oc Ar mm Oc Ar dd Oc Ar HH
61 .Fl f Ar input_fmt new_date
62 .Op Cm + Ns Ar output_fmt
71 When invoked without arguments, the
73 utility displays the current date and time.
74 Otherwise, depending on the options specified,
76 will set the date and time or print it in a user-defined way.
80 utility displays the date and time read from the kernel clock.
81 When used to set the date and time,
82 both the kernel clock and the hardware clock are updated.
84 Only the superuser may set the date,
85 and if the system securelevel (see
88 the time may not be changed by more than 1 second.
90 The options are as follows:
95 as the format string to parse the
97 provided rather than using the default
108 Parsing is done using
110 .It Fl I Ns Op Ar FMT
115 may be omitted, in which case the default is
125 The date and time is formatted to the specified precision.
128 format includes the timezone, except when
133 Do not try to set the date.
134 This allows you to use the
136 flag in addition to the
138 option to convert one date format to another.
140 Obsolete flag, accepted and ignored for compatibility.
142 Use RFC 2822 date and time output format. This is equivalent to use
143 .Dq Li %a, %d %b %Y \&%T %z
152 Print the date and time represented by
156 is the number of seconds since the Epoch
157 (00:00:00 UTC, January 1, 1970;
160 and can be specified in decimal, octal, or hex.
162 Display or set the date in
164 (Coordinated Universal) time.
166 For some compatibility with gnu date, the
168 option is an alias for the
171 In addition to the formats already supported, we now support
173 (seconds, minutes, hours, months, years, and abbreviations of same),
176 several month, day, and year arrangements, h:m[:s], and a few other
178 Not all of these can be combined with prefixes and there is still a lot
179 of missing support for gnu date compatibility.
180 In particular the handling of TZ= timezone specifications is mis-applied
181 and support for the "Z" suffix is missing.
183 Adjust (i.e., take the current date and display the result of the
184 adjustment; not actually set the date) the second, minute, hour, month
185 day, week day, month or year according to
189 is preceded with a plus or minus sign,
190 the date is adjusted forwards or backwards according to the remaining string,
191 otherwise the relevant part of the date is set.
192 The date can be adjusted as many times as required using these flags.
193 Flags are processed in the order given.
196 (rather than adjusting them),
197 seconds are in the range 0-59, minutes are in the range 0-59, hours are
198 in the range 0-23, month days are in the range 1-31, week days are in the
200 months are in the range 1-12 (Jan-Dec)
201 and years are in the range 80-38 or 1980-2038.
205 is numeric, one of either
214 must be used to specify which part of the date is to be adjusted.
216 The week day or month may be specified using a name rather than a
218 If a name is used with the plus
220 sign, the date will be put forwards
224 date that matches the given week day or month.
225 This will not adjust the date,
226 if the given week day or month is the same as the current one.
228 When a date is adjusted to a specific value or in units greater than hours,
229 daylight savings time considerations are ignored.
230 Adjustments in units of hours or less honor daylight saving time.
231 So, assuming the current date is March 26, 0:30 and that the DST adjustment
232 means that the clock goes forward at 01:00 to 02:00, using
234 will adjust the date to March 26, 2:30.
235 Likewise, if the date is October 29, 0:30 and the DST adjustment means that
236 the clock goes back at 02:00 to 01:00, using
238 will be necessary to reach October 29, 2:30.
240 When the date is adjusted to a specific value that does not actually exist
241 (for example March 26, 1:30 BST 2000 in the Europe/London timezone),
242 the date will be silently adjusted forwards in units of one hour until it
243 reaches a valid time.
244 When the date is adjusted to a specific value that occurs twice
245 (for example October 29, 1:30 2000),
246 the resulting timezone will be set so that the date matches the earlier of
249 Adjusting the date by months is inherently ambiguous because
250 a month is a unit of variable length depending on the current date.
251 This kind of date adjustment is applied in the most intuitive way.
254 tries to preserve the day of the month.
255 If it is impossible because the target month is shorter than the present one,
256 the last day of the target month will be the result.
259 on May 31 will adjust the date to June 30, while using the same option
260 on January 30 will result in the date adjusted to the last day of February.
261 This approach is also believed to make the most sense for shell scripting.
262 Nevertheless, be aware that going forth and back by the same number of
263 months may take you to a different date.
265 Refer to the examples below for further details.
268 An operand with a leading plus
270 sign signals a user-defined format string
271 which specifies the format in which to display the date and time.
272 The format string may contain any of the conversion specifications
275 manual page, as well as any arbitrary text.
278 character is always output after the characters specified by
280 The format string for the default display is
283 If an operand does not have a leading plus sign, it is interpreted as
284 a value for setting the system's notion of the current date and time.
285 The canonical representation for setting the date and time is:
287 .Bl -tag -width Ds -compact -offset indent
291 prepended to the abbreviated year.
293 Year in abbreviated form
294 (e.g., 89 for 1989, 06 for 2006).
296 Numeric month, a number from 1 to 12.
298 Day, a number from 1 to 31.
300 Hour, a number from 0 to 23.
302 Minutes, a number from 0 to 59.
304 Seconds, a number from 0 to 61
305 (59 plus a maximum of two leap seconds).
308 Everything but the minutes is optional.
310 Time changes for Daylight Saving Time, standard time, leap seconds,
311 and leap years are handled automatically.
313 The following environment variables affect the execution of
317 The timezone to use when displaying dates.
318 The normal format is a pathname relative to
319 .Pa /usr/share/zoneinfo .
320 For example, the command
321 .Dq TZ=America/Los_Angeles date
322 displays the current time in California.
325 for more information.
328 .Bl -tag -width /var/log/messages -compact
329 .It Pa /var/log/wtmpx
330 record of date resets and time changes
331 .It Pa /var/log/messages
332 record of the user setting the time
337 utility exits 0 on success, 1 if unable to set the date, and 2
338 if able to set the local date, but unable to set it globally.
342 .Dl "date ""+DATE: %Y-%m-%d%nTIME: %H:%M:%S"""
345 .Bd -literal -offset indent
350 In the Europe/London timezone, the command:
352 .Dl "date -v1m -v+1y"
356 .Dl "Sun Jan 4 04:15:24 GMT 1998"
358 where it is currently
359 .Li "Mon Aug 4 04:15:24 BST 1997" .
363 .Dl "date -v1d -v3m -v0y -v-1d"
365 will display the last day of February in the year 2000:
367 .Dl "Tue Feb 29 03:18:00 GMT 2000"
369 So will do the command:
371 .Dl "date -v30d -v3m -v0y -v-1m"
373 because there is no such date as the 30th of February.
377 .Dl "date -v1d -v+1m -v-1d -v-fri"
379 will display the last Friday of the month:
381 .Dl "Fri Aug 29 04:31:11 BST 1997"
383 where it is currently
384 .Li "Mon Aug 4 04:31:11 BST 1997" .
388 .Dl "date 8506131627"
391 .Dq Li "June 13, 1985, 4:27 PM" .
393 .Dl "date ""+%Y%m%d%H%M.%S"""
395 may be used on one machine to print out the date
396 suitable for setting on another.
397 .Qq ( Li "+%m%d%H%M%Y.%S"
407 without modifying the date.
411 .Dl "TZ=America/Los_Angeles date -Iseconds -r 1533415339"
415 .Dl "2018-08-04T13:42:19-07:00"
419 .Dl "date -j -f ""%a %b %d %T %Z %Y"" ""`date`"" ""+%s"""
421 can be used to parse the output from
423 and express it in Epoch time.
432 utility is expected to be compatible with
435 The format selected by the
437 flag is compatible with