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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 $
34 .Dd September 11, 2019
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
64 When invoked without arguments, the
66 utility displays the current date and time.
67 Otherwise, depending on the options specified,
69 will set the date and time or print it in a user-defined way.
73 utility displays the date and time read from the kernel clock.
74 When used to set the date and time,
75 both the kernel clock and the hardware clock are updated.
77 Only the superuser may set the date,
78 and if the system securelevel (see
81 the time may not be changed by more than 1 second.
83 The options are as follows:
88 as the format string to parse the
90 provided rather than using the default
101 Parsing is done using
104 Do not try to set the date.
105 This allows you to use the
107 flag in addition to the
109 option to convert one date format to another.
111 Obsolete flag, accepted and ignored for compatibility.
113 Use RFC 2822 date and time output format. This is equivalent to use
114 .Dq Li %a, %d %b %Y \&%T %z
123 Print the date and time represented by
127 is the number of seconds since the Epoch
128 (00:00:00 UTC, January 1, 1970;
131 and can be specified in decimal, octal, or hex.
133 Display or set the date in
135 (Coordinated Universal) time.
137 Adjust (i.e., take the current date and display the result of the
138 adjustment; not actually set the date) the second, minute, hour, month
139 day, week day, month or year according to
143 is preceded with a plus or minus sign,
144 the date is adjusted forwards or backwards according to the remaining string,
145 otherwise the relevant part of the date is set.
146 The date can be adjusted as many times as required using these flags.
147 Flags are processed in the order given.
150 (rather than adjusting them),
151 seconds are in the range 0-59, minutes are in the range 0-59, hours are
152 in the range 0-23, month days are in the range 1-31, week days are in the
154 months are in the range 1-12 (Jan-Dec)
155 and years are in the range 80-38 or 1980-2038.
159 is numeric, one of either
168 must be used to specify which part of the date is to be adjusted.
170 The week day or month may be specified using a name rather than a
172 If a name is used with the plus
174 sign, the date will be put forwards
178 date that matches the given week day or month.
179 This will not adjust the date,
180 if the given week day or month is the same as the current one.
182 When a date is adjusted to a specific value or in units greater than hours,
183 daylight savings time considerations are ignored.
184 Adjustments in units of hours or less honor daylight saving time.
185 So, assuming the current date is March 26, 0:30 and that the DST adjustment
186 means that the clock goes forward at 01:00 to 02:00, using
188 will adjust the date to March 26, 2:30.
189 Likewise, if the date is October 29, 0:30 and the DST adjustment means that
190 the clock goes back at 02:00 to 01:00, using
192 will be necessary to reach October 29, 2:30.
194 When the date is adjusted to a specific value that does not actually exist
195 (for example March 26, 1:30 BST 2000 in the Europe/London timezone),
196 the date will be silently adjusted forwards in units of one hour until it
197 reaches a valid time.
198 When the date is adjusted to a specific value that occurs twice
199 (for example October 29, 1:30 2000),
200 the resulting timezone will be set so that the date matches the earlier of
203 Adjusting the date by months is inherently ambiguous because
204 a month is a unit of variable length depending on the current date.
205 This kind of date adjustment is applied in the most intuitive way.
208 tries to preserve the day of the month.
209 If it is impossible because the target month is shorter than the present one,
210 the last day of the target month will be the result.
213 on May 31 will adjust the date to June 30, while using the same option
214 on January 30 will result in the date adjusted to the last day of February.
215 This approach is also believed to make the most sense for shell scripting.
216 Nevertheless, be aware that going forth and back by the same number of
217 months may take you to a different date.
219 Refer to the examples below for further details.
222 An operand with a leading plus
224 sign signals a user-defined format string
225 which specifies the format in which to display the date and time.
226 The format string may contain any of the conversion specifications
229 manual page, as well as any arbitrary text.
232 character is always output after the characters specified by
234 The format string for the default display is
237 If an operand does not have a leading plus sign, it is interpreted as
238 a value for setting the system's notion of the current date and time.
239 The canonical representation for setting the date and time is:
241 .Bl -tag -width Ds -compact -offset indent
245 prepended to the abbreviated year.
247 Year in abbreviated form
248 (e.g., 89 for 1989, 06 for 2006).
250 Numeric month, a number from 1 to 12.
252 Day, a number from 1 to 31.
254 Hour, a number from 0 to 23.
256 Minutes, a number from 0 to 59.
258 Seconds, a number from 0 to 61
259 (59 plus a maximum of two leap seconds).
262 Everything but the minutes is optional.
264 Time changes for Daylight Saving Time, standard time, leap seconds,
265 and leap years are handled automatically.
267 The following environment variables affect the execution of
271 The timezone to use when displaying dates.
272 The normal format is a pathname relative to
273 .Pa /usr/share/zoneinfo .
274 For example, the command
275 .Dq TZ=America/Los_Angeles date
276 displays the current time in California.
279 for more information.
282 .Bl -tag -width /var/log/messages -compact
283 .It Pa /var/log/wtmpx
284 record of date resets and time changes
285 .It Pa /var/log/messages
286 record of the user setting the time
291 utility exits 0 on success, 1 if unable to set the date, and 2
292 if able to set the local date, but unable to set it globally.
296 .Dl "date ""+DATE: %Y-%m-%d%nTIME: %H:%M:%S"""
299 .Bd -literal -offset indent
304 In the Europe/London timezone, the command:
306 .Dl "date -v1m -v+1y"
310 .Dl "Sun Jan 4 04:15:24 GMT 1998"
312 where it is currently
313 .Li "Mon Aug 4 04:15:24 BST 1997" .
317 .Dl "date -v1d -v3m -v0y -v-1d"
319 will display the last day of February in the year 2000:
321 .Dl "Tue Feb 29 03:18:00 GMT 2000"
323 So will do the command:
325 .Dl "date -v30d -v3m -v0y -v-1m"
327 because there is no such date as the 30th of February.
331 .Dl "date -v1d -v+1m -v-1d -v-fri"
333 will display the last Friday of the month:
335 .Dl "Fri Aug 29 04:31:11 BST 1997"
337 where it is currently
338 .Li "Mon Aug 4 04:31:11 BST 1997" .
342 .Dl "date 8506131627"
345 .Dq Li "June 13, 1985, 4:27 PM" .
347 .Dl "date ""+%Y%m%d%H%M.%S"""
349 may be used on one machine to print out the date
350 suitable for setting on another.
351 .Qq ( Li "+%m%d%H%M%Y.%S"
361 without modifying the date.
365 .Dl "date -j -f ""%a %b %d %T %Z %Y"" ""`date`"" ""+%s"""
367 can be used to parse the output from
369 and express it in Epoch time.
378 utility is expected to be compatible with