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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.
146 Obsolete flag, accepted and ignored for compatibility.
148 Use RFC 2822 date and time output format.
149 This is equivalent to using
150 .Dq Li %a, %d %b %Y \&%T %z
159 Print the date and time represented by
163 is the number of seconds since the Epoch
164 (00:00:00 UTC, January 1, 1970;
167 and can be specified in decimal, octal, or hex.
169 Print the date and time of the last modification of
172 Display or set the date in
174 (Coordinated Universal) time.
176 Adjust (i.e., take the current date and display the result of the
177 adjustment; not actually set the date) the second, minute, hour, month
178 day, week day, month or year according to
182 is preceded with a plus or minus sign,
183 the date is adjusted forwards or backwards according to the remaining string,
184 otherwise the relevant part of the date is set.
185 The date can be adjusted as many times as required using these flags.
186 Flags are processed in the order given.
189 (rather than adjusting them),
190 seconds are in the range 0-59, minutes are in the range 0-59, hours are
191 in the range 0-23, month days are in the range 1-31, week days are in the
193 months are in the range 1-12 (Jan-Dec)
194 and years are in the range 80-38 or 1980-2038.
198 is numeric, one of either
207 must be used to specify which part of the date is to be adjusted.
209 The week day or month may be specified using a name rather than a
211 If a name is used with the plus
213 sign, the date will be put forwards
217 date that matches the given week day or month.
218 This will not adjust the date,
219 if the given week day or month is the same as the current one.
221 When a date is adjusted to a specific value or in units greater than hours,
222 daylight savings time considerations are ignored.
223 Adjustments in units of hours or less honor daylight saving time.
224 So, assuming the current date is March 26, 0:30 and that the DST adjustment
225 means that the clock goes forward at 01:00 to 02:00, using
227 will adjust the date to March 26, 2:30.
228 Likewise, if the date is October 29, 0:30 and the DST adjustment means that
229 the clock goes back at 02:00 to 01:00, using
231 will be necessary to reach October 29, 2:30.
233 When the date is adjusted to a specific value that does not actually exist
234 (for example March 26, 1:30 BST 2000 in the Europe/London timezone),
235 the date will be silently adjusted forwards in units of one hour until it
236 reaches a valid time.
237 When the date is adjusted to a specific value that occurs twice
238 (for example October 29, 1:30 2000),
239 the resulting timezone will be set so that the date matches the earlier of
242 It is not possible to adjust a date to an invalid absolute day, so using
244 .Fl v No 31d Fl v No 12m
245 will simply fail five months of the year.
246 It is therefore usual to set the month before setting the day; using
247 .Fl v No 12m Fl v No 31d
250 Adjusting the date by months is inherently ambiguous because
251 a month is a unit of variable length depending on the current date.
252 This kind of date adjustment is applied in the most intuitive way.
255 tries to preserve the day of the month.
256 If it is impossible because the target month is shorter than the present one,
257 the last day of the target month will be the result.
260 on May 31 will adjust the date to June 30, while using the same option
261 on January 30 will result in the date adjusted to the last day of February.
262 This approach is also believed to make the most sense for shell scripting.
263 Nevertheless, be aware that going forth and back by the same number of
264 months may take you to a different date.
266 Refer to the examples below for further details.
269 An operand with a leading plus
271 sign signals a user-defined format string
272 which specifies the format in which to display the date and time.
273 The format string may contain any of the conversion specifications
276 manual page, as well as any arbitrary text.
279 character is always output after the characters specified by
281 The format string for the default display is
284 If an operand does not have a leading plus sign, it is interpreted as
285 a value for setting the system's notion of the current date and time.
286 The canonical representation for setting the date and time is:
288 .Bl -tag -width Ds -compact -offset indent
292 prepended to the abbreviated year.
294 Year in abbreviated form
295 (e.g., 89 for 1989, 06 for 2006).
297 Numeric month, a number from 1 to 12.
299 Day, a number from 1 to 31.
301 Hour, a number from 0 to 23.
303 Minutes, a number from 0 to 59.
305 Seconds, a number from 0 to 60
306 (59 plus a potential leap second).
309 Everything but the minutes is optional.
311 Time changes for Daylight Saving Time, standard time, leap seconds,
312 and leap years are handled automatically.
314 The following environment variables affect the execution of
318 The timezone to use when displaying dates.
319 The normal format is a pathname relative to
320 .Pa /usr/share/zoneinfo .
321 For example, the command
322 .Dq TZ=America/Los_Angeles date
323 displays the current time in California.
326 for more information.
329 .Bl -tag -width /var/log/messages -compact
330 .It Pa /var/log/utx.log
331 record of date resets and time changes
332 .It Pa /var/log/messages
333 record of the user setting the time
338 utility exits 0 on success, 1 if unable to set the date, and 2
339 if able to set the local date, but unable to set it globally.
343 .Dl "date ""+DATE: %Y-%m-%d%nTIME: %H:%M:%S"""
346 .Bd -literal -offset indent
351 In the Europe/London timezone, the command:
353 .Dl "date -v1m -v+1y"
357 .Dl "Sun Jan 4 04:15:24 GMT 1998"
359 where it is currently
360 .Li "Mon Aug 4 04:15:24 BST 1997" .
364 .Dl "date -v1d -v3m -v0y -v-1d"
366 will display the last day of February in the year 2000:
368 .Dl "Tue Feb 29 03:18:00 GMT 2000"
372 .Dl "date -v3m -v30d -v0y -v-1m"
374 because there is no such date as the 30th of February.
378 .Dl "date -v1d -v+1m -v-1d -v-fri"
380 will display the last Friday of the month:
382 .Dl "Fri Aug 29 04:31:11 BST 1997"
384 where it is currently
385 .Li "Mon Aug 4 04:31:11 BST 1997" .
389 .Dl "date 8506131627"
392 .Dq Li "June 13, 1985, 4:27 PM" .
394 .Dl "date ""+%Y%m%d%H%M.%S"""
396 may be used on one machine to print out the date
397 suitable for setting on another.
398 .Qq ( Li "+%m%d%H%M%Y.%S"
408 without modifying the date.
412 .Dl "TZ=America/Los_Angeles date -Iseconds -r 1533415339"
416 .Dl "2018-08-04T13:42:19-07:00"
420 .Dl "date -j -f ""%a %b %d %T %Z %Y"" ""`date`"" ""+%s"""
422 can be used to parse the output from
424 and express it in Epoch time.
426 It is invalid to combine the
436 .Ql multiple output formats specified
437 and exits with an error status.
445 .%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD"
452 utility is expected to be compatible with
455 .Fl d , f , I , j , r , t ,
458 options are all extensions to the standard.
460 The format selected by the
462 flag is compatible with