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32 .\" @(#)date.1 8.3 (Berkeley) 4/28/95
40 .Nd display or set date and time
44 .Op Fl r Ar seconds | Ar filename
53 .Op Cm + Ns Ar output_fmt
57 .Op Oo Oo Oo Oo Ar cc Oc Ar yy Oc Ar mm Oc Ar dd Oc Ar HH
62 .Fl f Ar input_fmt new_date
63 .Op Cm + Ns Ar output_fmt
72 When invoked without arguments, the
74 utility displays the current date and time.
75 Otherwise, depending on the options specified,
77 will set the date and time or print it in a user-defined way.
81 utility displays the date and time read from the kernel clock.
82 When used to set the date and time,
83 both the kernel clock and the hardware clock are updated.
85 Only the superuser may set the date,
86 and if the system securelevel (see
89 the time may not be changed by more than 1 second.
91 The options are as follows:
96 as the format string to parse the
98 provided rather than using the default
109 Parsing is done using
111 .It Fl I Ns Op Ar FMT
116 may be omitted, in which case the default is
126 The date and time is formatted to the specified precision.
137 format includes the timezone.
139 Do not try to set the date.
140 This allows you to use the
142 flag in addition to the
144 option to convert one date format to another.
150 sets the time on all of the machines in the local group.
153 option suppresses this behavior and causes the time to be set only on the
156 Use RFC 2822 date and time output format.
157 This is equivalent to using
158 .Dq Li %a, %d %b %Y \&%T %z
167 Print the date and time represented by
171 is the number of seconds since the Epoch
172 (00:00:00 UTC, January 1, 1970;
175 and can be specified in decimal, octal, or hex.
177 Print the date and time of the last modification of
180 Display or set the date in
182 (Coordinated Universal) time.
184 Adjust (i.e., take the current date and display the result of the
185 adjustment; not actually set the date) the second, minute, hour, month
186 day, week day, month or year according to
190 is preceded with a plus or minus sign,
191 the date is adjusted forwards or backwards according to the remaining string,
192 otherwise the relevant part of the date is set.
193 The date can be adjusted as many times as required using these flags.
194 Flags are processed in the order given.
197 (rather than adjusting them),
198 seconds are in the range 0-59, minutes are in the range 0-59, hours are
199 in the range 0-23, month days are in the range 1-31, week days are in the
201 months are in the range 1-12 (Jan-Dec)
202 and years are in the range 80-38 or 1980-2038.
206 is numeric, one of either
215 must be used to specify which part of the date is to be adjusted.
217 The week day or month may be specified using a name rather than a
219 If a name is used with the plus
221 sign, the date will be put forwards
225 date that matches the given week day or month.
226 This will not adjust the date,
227 if the given week day or month is the same as the current one.
229 When a date is adjusted to a specific value or in units greater than hours,
230 daylight savings time considerations are ignored.
231 Adjustments in units of hours or less honor daylight saving time.
232 So, assuming the current date is March 26, 0:30 and that the DST adjustment
233 means that the clock goes forward at 01:00 to 02:00, using
235 will adjust the date to March 26, 2:30.
236 Likewise, if the date is October 29, 0:30 and the DST adjustment means that
237 the clock goes back at 02:00 to 01:00, using
239 will be necessary to reach October 29, 2:30.
241 When the date is adjusted to a specific value that does not actually exist
242 (for example March 26, 1:30 BST 2000 in the Europe/London timezone),
243 the date will be silently adjusted forwards in units of one hour until it
244 reaches a valid time.
245 When the date is adjusted to a specific value that occurs twice
246 (for example October 29, 1:30 2000),
247 the resulting timezone will be set so that the date matches the earlier of
250 It is not possible to adjust a date to an invalid absolute day, so using
252 .Fl v No 31d Fl v No 12m
253 will simply fail five months of the year.
254 It is therefore usual to set the month before setting the day; using
255 .Fl v No 12m Fl v No 31d
258 Adjusting the date by months is inherently ambiguous because
259 a month is a unit of variable length depending on the current date.
260 This kind of date adjustment is applied in the most intuitive way.
263 tries to preserve the day of the month.
264 If it is impossible because the target month is shorter than the present one,
265 the last day of the target month will be the result.
268 on May 31 will adjust the date to June 30, while using the same option
269 on January 30 will result in the date adjusted to the last day of February.
270 This approach is also believed to make the most sense for shell scripting.
271 Nevertheless, be aware that going forth and back by the same number of
272 months may take you to a different date.
274 Refer to the examples below for further details.
277 An operand with a leading plus
279 sign signals a user-defined format string
280 which specifies the format in which to display the date and time.
281 The format string may contain any of the conversion specifications
284 manual page, as well as any arbitrary text.
287 character is always output after the characters specified by
289 The format string for the default display is
292 If an operand does not have a leading plus sign, it is interpreted as
293 a value for setting the system's notion of the current date and time.
294 The canonical representation for setting the date and time is:
296 .Bl -tag -width Ds -compact -offset indent
300 prepended to the abbreviated year.
302 Year in abbreviated form
303 (e.g., 89 for 1989, 06 for 2006).
305 Numeric month, a number from 1 to 12.
307 Day, a number from 1 to 31.
309 Hour, a number from 0 to 23.
311 Minutes, a number from 0 to 59.
313 Seconds, a number from 0 to 60
314 (59 plus a potential leap second).
317 Everything but the minutes is optional.
319 Time changes for Daylight Saving Time, standard time, leap seconds,
320 and leap years are handled automatically.
322 The following environment variables affect the execution of
326 The timezone to use when displaying dates.
327 The normal format is a pathname relative to
328 .Pa /usr/share/zoneinfo .
329 For example, the command
330 .Dq TZ=America/Los_Angeles date
331 displays the current time in California.
334 for more information.
337 .Bl -tag -width /var/log/messages -compact
338 .It Pa /var/log/utx.log
339 record of date resets and time changes
340 .It Pa /var/log/messages
341 record of the user setting the time
346 utility exits 0 on success, 1 if unable to set the date, and 2
347 if able to set the local date, but unable to set it globally.
351 .Dl "date ""+DATE: %Y-%m-%d%nTIME: %H:%M:%S"""
354 .Bd -literal -offset indent
359 In the Europe/London timezone, the command:
361 .Dl "date -v1m -v+1y"
365 .Dl "Sun Jan 4 04:15:24 GMT 1998"
367 where it is currently
368 .Li "Mon Aug 4 04:15:24 BST 1997" .
372 .Dl "date -v1d -v3m -v0y -v-1d"
374 will display the last day of February in the year 2000:
376 .Dl "Tue Feb 29 03:18:00 GMT 2000"
380 .Dl "date -v3m -v30d -v0y -v-1m"
382 because there is no such date as the 30th of February.
386 .Dl "date -v1d -v+1m -v-1d -v-fri"
388 will display the last Friday of the month:
390 .Dl "Fri Aug 29 04:31:11 BST 1997"
392 where it is currently
393 .Li "Mon Aug 4 04:31:11 BST 1997" .
397 .Dl "date 8506131627"
400 .Dq Li "June 13, 1985, 4:27 PM" .
402 .Dl "date ""+%Y%m%d%H%M.%S"""
404 may be used on one machine to print out the date
405 suitable for setting on another.
406 .Qq ( Li "+%m%d%H%M%Y.%S"
416 without modifying the date.
420 .Dl "TZ=America/Los_Angeles date -Iseconds -r 1533415339"
424 .Dl "2018-08-04T13:42:19-07:00"
428 .Dl "date -j -f ""%a %b %d %T %Z %Y"" ""`date`"" ""+%s"""
430 can be used to parse the output from
432 and express it in Epoch time.
436 synchronizes the time on many hosts, the setting of a new time value may
437 require more than a few seconds.
441 .Ql Network time being set .
443 .Ql Communication error with timed
444 occurs when the communication
451 It is invalid to combine the
461 .Ql multiple output formats specified
462 and exits with an error status.
471 .%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD"
478 utility is expected to be compatible with
481 .Fl d , f , I , j , n , r , t ,
484 options are all extensions to the standard.
486 The format selected by the
488 flag is compatible with