1 .\" Copyright (c) 1980, 1990, 1993
2 .\" The Regents of the University of California. All rights reserved.
4 .\" This code is derived from software contributed to Berkeley by
5 .\" the Institute of Electrical and Electronics Engineers, Inc.
7 .\" Redistribution and use in source and binary forms, with or without
8 .\" modification, are permitted provided that the following conditions
10 .\" 1. Redistributions of source code must retain the above copyright
11 .\" notice, this list of conditions and the following disclaimer.
12 .\" 2. Redistributions in binary form must reproduce the above copyright
13 .\" notice, this list of conditions and the following disclaimer in the
14 .\" documentation and/or other materials provided with the distribution.
15 .\" 3. Neither the name of the University nor the names of its contributors
16 .\" may be used to endorse or promote products derived from this software
17 .\" without specific prior written permission.
19 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 $
33 .\" $DragonFly: src/bin/date/date.1,v 1.4 2005/07/20 20:05:46 cpressey Exp $
40 .Nd display or set date and time
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
66 .Op Fl t Ar minutes_west
68 When invoked without arguments, the
70 utility displays the current date and time.
71 Otherwise, depending on the options specified,
73 will set the date and time or print it in a user-defined way.
77 utility displays the date and time read from the kernel clock.
78 When used to set the date and time,
79 both the kernel clock and the hardware clock are updated.
81 Only the superuser may set the date,
82 and if the system securelevel (see
85 the time may not be changed by more than 1 second.
87 The options are as follows:
90 Set the kernel's value for daylight saving time.
93 is non-zero, future calls
96 will return a non-zero for
101 as the format string to parse the
103 provided rather than using the default
114 Parsing is done using
117 Do not try to set the date.
118 This allows you to use the
120 flag in addition to the
122 option to convert one date format to another.
128 sets the time on all of the machines in the local group.
131 option suppresses this behavior and causes the time to be set only on the
134 Print the date and time represented by
138 is the number of seconds since the Epoch
139 (00:00:00 UTC, January 1, 1970;
142 and can be specified in decimal, octal, or hex.
143 .It Fl t Ar minutes_west
144 Set the system's value for minutes west of
147 specifies the number of minutes returned in
152 Display or set the date in
154 (Coordinated Universal) time.
156 Adjust (i.e., take the current date and display the result of the
157 adjustment; not actually set the date) the second, minute, hour, month
158 day, week day, month or year according to
162 is preceded with a plus or minus sign,
163 the date is adjusted forwards or backwards according to the remaining string,
164 otherwise the relevant part of the date is set.
165 The date can be adjusted as many times as required using these flags.
166 Flags are processed in the order given.
169 (rather than adjusting them),
170 seconds are in the range 0-59, minutes are in the range 0-59, hours are
171 in the range 0-23, month days are in the range 1-31, week days are in the
173 months are in the range 1-12 (Jan-Dec)
174 and years are in the range 80-38 or 1980-2038.
178 is numeric, one of either
187 must be used to specify which part of the date is to be adjusted.
189 The week day or month may be specified using a name rather than a
191 If a name is used with the plus
193 sign, the date will be put forwards
197 date that matches the given week day or month.
198 This will not adjust the date,
199 if the given week day or month is the same as the current one.
201 When a date is adjusted to a specific value or in units greater than hours,
202 daylight savings time considerations are ignored.
203 Adjustments in units of hours or less honor daylight saving time.
204 So, assuming the current date is March 26, 0:30 and that the DST adjustment
205 means that the clock goes forward at 01:00 to 02:00, using
207 will adjust the date to March 26, 2:30.
208 Likewise, if the date is October 29, 0:30 and the DST adjustment means that
209 the clock goes back at 02:00 to 01:00, using
211 will be necessary to reach October 29, 2:30.
213 When the date is adjusted to a specific value that does not actually exist
214 (for example March 26, 1:30 BST 2000 in the Europe/London timezone),
215 the date will be silently adjusted forwards in units of one hour until it
216 reaches a valid time.
217 When the date is adjusted to a specific value that occurs twice
218 (for example October 29, 1:30 2000),
219 the resulting timezone will be set so that the date matches the earlier of
222 Adjusting the date by months is inherently ambiguous because
223 a month is a unit of variable length depending on the current date.
224 This kind of date adjustment is applied in the most intuitive way.
227 tries to preserve the day of the month.
228 If it is impossible because the target month is shorter than the present one,
229 the last day of the target month will be the result.
232 on May 31 will adjust the date to June 30, while using the same option
233 on January 30 will result in the date adjusted to the last day of February.
234 This approach is also believed to make the most sense for shell scripting.
235 Nevertheless, be aware that going forth and back by the same number of
236 months may take you to a different date.
238 Refer to the examples below for further details.
241 An operand with a leading plus
243 sign signals a user-defined format string
244 which specifies the format in which to display the date and time.
245 The format string may contain any of the conversion specifications
248 manual page, as well as any arbitrary text.
251 character is always output after the characters specified by
253 The format string for the default display is
256 If an operand does not have a leading plus sign, it is interpreted as
257 a value for setting the system's notion of the current date and time.
258 The canonical representation for setting the date and time is:
260 .Bl -tag -width Ds -compact -offset indent
264 prepended to the abbreviated year.
266 Year in abbreviated form
267 (e.g., 89 for 1989, 06 for 2006).
269 Numeric month, a number from 1 to 12.
271 Day, a number from 1 to 31.
273 Hour, a number from 0 to 23.
275 Minutes, a number from 0 to 59.
277 Seconds, a number from 0 to 61
278 (59 plus a maximum of two leap seconds).
281 Everything but the minutes is optional.
283 Time changes for Daylight Saving Time, standard time, leap seconds,
284 and leap years are handled automatically.
286 The following environment variables affect the execution of
290 The timezone to use when displaying dates.
291 The normal format is a pathname relative to
292 .Pa /usr/share/zoneinfo .
293 For example, the command
294 .Dq TZ=America/Los_Angeles date
295 displays the current time in California.
298 for more information.
301 .Bl -tag -width /var/log/messages -compact
303 record of date resets and time changes
304 .It Pa /var/log/messages
305 record of the user setting the time
310 utility exits 0 on success, 1 if unable to set the date, and 2
311 if able to set the local date, but unable to set it globally.
315 .Dl "date ""+DATE: %Y-%m-%d%nTIME: %H:%M:%S"""
318 .Bd -literal -offset indent
323 In the Europe/London timezone, the command:
325 .Dl "date -v1m -v+1y"
329 .Dl "Sun Jan 4 04:15:24 GMT 1998"
331 where it is currently
332 .Li "Mon Aug 4 04:15:24 BST 1997" .
336 .Dl "date -v1d -v3m -v0y -v-1d"
338 will display the last day of February in the year 2000:
340 .Dl "Tue Feb 29 03:18:00 GMT 2000"
342 So will do the command:
344 .Dl "date -v30d -v3m -v0y -v-1m"
346 because there is no such date as the 30th of February.
350 .Dl "date -v1d -v+1m -v-1d -v-fri"
352 will display the last Friday of the month:
354 .Dl "Fri Aug 29 04:31:11 BST 1997"
356 where it is currently
357 .Li "Mon Aug 4 04:31:11 BST 1997" .
361 .Dl "date 8506131627"
364 .Dq Li "June 13, 1985, 4:27 PM" .
366 .Dl "date ""+%Y%m%d%H%M.%S"""
368 may be used on one machine to print out the date
369 suitable for setting on another.
370 .Qq ( Li "+%m%d%H%M%Y.%S"
380 without modifying the date.
384 .Dl "date -j -f ""%a %b %d %T %Z %Y"" ""`date`"" ""+%s"""
386 can be used to parse the output from
388 and express it in Epoch time.
392 synchronizes the time on many hosts, the setting of a new time value may
393 require more than a few seconds.
397 .Ql Network time being set .
399 .Ql Communication error with timed
400 occurs when the communication
413 .%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD"
420 utility is expected to be compatible with