1.\"- 2.\" Copyright (c) 1980, 1990, 1993 3.\" The Regents of the University of California. All rights reserved. 4.\" 5.\" This code is derived from software contributed to Berkeley by 6.\" the Institute of Electrical and Electronics Engineers, Inc. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)date.1 8.3 (Berkeley) 4/28/95 33.\" $FreeBSD$ 34.\" 35.Dd August 4, 2018 36.Dt DATE 1 37.Os 38.Sh NAME 39.Nm date 40.Nd display or set date and time 41.Sh SYNOPSIS 42.Nm 43.Op Fl jRu 44.Op Fl r Ar seconds | Ar filename 45.Oo 46.Fl v 47.Sm off 48.Op Cm + | - 49.Ar val Op Ar ymwdHMS 50.Sm on 51.Oc 52.Ar ... 53.Op Cm + Ns Ar output_fmt 54.Nm 55.Op Fl jnu 56.Sm off 57.Op Oo Oo Oo Oo Ar cc Oc Ar yy Oc Ar mm Oc Ar dd Oc Ar HH 58.Ar MM Op Ar .ss 59.Sm on 60.Nm 61.Op Fl jnRu 62.Fl f Ar input_fmt new_date 63.Op Cm + Ns Ar output_fmt 64.Nm 65.Op Fl d Ar dst 66.Op Fl t Ar minutes_west 67.Nm 68.Op Fl jnu 69.Op Fl I Ns Op Ar FMT 70.Op Fl f Ar input_fmt 71.Op Fl r Ar ... 72.Op Fl v Ar ... 73.Op Ar new_date 74.Sh DESCRIPTION 75When invoked without arguments, the 76.Nm 77utility displays the current date and time. 78Otherwise, depending on the options specified, 79.Nm 80will set the date and time or print it in a user-defined way. 81.Pp 82The 83.Nm 84utility displays the date and time read from the kernel clock. 85When used to set the date and time, 86both the kernel clock and the hardware clock are updated. 87.Pp 88Only the superuser may set the date, 89and if the system securelevel (see 90.Xr securelevel 7 ) 91is greater than 1, 92the time may not be changed by more than 1 second. 93.Pp 94The options are as follows: 95.Bl -tag -width Ds 96.It Fl d Ar dst 97Set the kernel's value for daylight saving time. 98If 99.Ar dst 100is non-zero, future calls 101to 102.Xr gettimeofday 2 103will return a non-zero for 104.Fa tz_dsttime . 105.It Fl f 106Use 107.Ar input_fmt 108as the format string to parse the 109.Ar new_date 110provided rather than using the default 111.Sm off 112.Oo Oo Oo Oo Oo 113.Ar cc Oc 114.Ar yy Oc 115.Ar mm Oc 116.Ar dd Oc 117.Ar HH 118.Oc Ar MM Op Ar .ss 119.Sm on 120format. 121Parsing is done using 122.Xr strptime 3 . 123.It Fl I Ns Op Ar FMT 124Use 125.St -iso8601 126output format. 127.Ar FMT 128may be omitted, in which case the default is 129.Sq date . 130Valid 131.Ar FMT 132values are 133.Sq date , 134.Sq hours , 135.Sq minutes , 136and 137.Sq seconds . 138The date and time is formatted to the specified precision. 139When 140.Ar FMT 141is 142.Sq hours 143(or the more precise 144.Sq minutes 145or 146.Sq seconds ) , 147the 148.St -iso8601 149format includes the timezone. 150.It Fl j 151Do not try to set the date. 152This allows you to use the 153.Fl f 154flag in addition to the 155.Cm + 156option to convert one date format to another. 157.It Fl n 158By default, if the 159.Xr timed 8 160daemon is running, 161.Nm 162sets the time on all of the machines in the local group. 163The 164.Fl n 165option suppresses this behavior and causes the time to be set only on the 166current machine. 167.It Fl R 168Use RFC 2822 date and time output format. 169This is equivalent to using 170.Dq Li %a, %d %b %Y \&%T %z 171as 172.Ar output_fmt 173while 174.Ev LC_TIME 175is set to the 176.Dq C 177locale . 178.It Fl r Ar seconds 179Print the date and time represented by 180.Ar seconds , 181where 182.Ar seconds 183is the number of seconds since the Epoch 184(00:00:00 UTC, January 1, 1970; 185see 186.Xr time 3 ) , 187and can be specified in decimal, octal, or hex. 188.It Fl r Ar filename 189Print the date and time of the last modification of 190.Ar filename . 191.It Fl t Ar minutes_west 192Set the system's value for minutes west of 193.Tn GMT . 194.Ar minutes_west 195specifies the number of minutes returned in 196.Fa tz_minuteswest 197by future calls to 198.Xr gettimeofday 2 . 199.It Fl u 200Display or set the date in 201.Tn UTC 202(Coordinated Universal) time. 203.It Fl v 204Adjust (i.e., take the current date and display the result of the 205adjustment; not actually set the date) the second, minute, hour, month 206day, week day, month or year according to 207.Ar val . 208If 209.Ar val 210is preceded with a plus or minus sign, 211the date is adjusted forwards or backwards according to the remaining string, 212otherwise the relevant part of the date is set. 213The date can be adjusted as many times as required using these flags. 214Flags are processed in the order given. 215.Pp 216When setting values 217(rather than adjusting them), 218seconds are in the range 0-59, minutes are in the range 0-59, hours are 219in the range 0-23, month days are in the range 1-31, week days are in the 220range 0-6 (Sun-Sat), 221months are in the range 1-12 (Jan-Dec) 222and years are in the range 80-38 or 1980-2038. 223.Pp 224If 225.Ar val 226is numeric, one of either 227.Ar y , 228.Ar m , 229.Ar w , 230.Ar d , 231.Ar H , 232.Ar M 233or 234.Ar S 235must be used to specify which part of the date is to be adjusted. 236.Pp 237The week day or month may be specified using a name rather than a 238number. 239If a name is used with the plus 240(or minus) 241sign, the date will be put forwards 242(or backwards) 243to the next 244(previous) 245date that matches the given week day or month. 246This will not adjust the date, 247if the given week day or month is the same as the current one. 248.Pp 249When a date is adjusted to a specific value or in units greater than hours, 250daylight savings time considerations are ignored. 251Adjustments in units of hours or less honor daylight saving time. 252So, assuming the current date is March 26, 0:30 and that the DST adjustment 253means that the clock goes forward at 01:00 to 02:00, using 254.Fl v No +1H 255will adjust the date to March 26, 2:30. 256Likewise, if the date is October 29, 0:30 and the DST adjustment means that 257the clock goes back at 02:00 to 01:00, using 258.Fl v No +3H 259will be necessary to reach October 29, 2:30. 260.Pp 261When the date is adjusted to a specific value that does not actually exist 262(for example March 26, 1:30 BST 2000 in the Europe/London timezone), 263the date will be silently adjusted forwards in units of one hour until it 264reaches a valid time. 265When the date is adjusted to a specific value that occurs twice 266(for example October 29, 1:30 2000), 267the resulting timezone will be set so that the date matches the earlier of 268the two times. 269.Pp 270It is not possible to adjust a date to an invalid absolute day, so using 271the switches 272.Fl v No 31d Fl v No 12m 273will simply fail five months of the year. 274It is therefore usual to set the month before setting the day; using 275.Fl v No 12m Fl v No 31d 276always works. 277.Pp 278Adjusting the date by months is inherently ambiguous because 279a month is a unit of variable length depending on the current date. 280This kind of date adjustment is applied in the most intuitive way. 281First of all, 282.Nm 283tries to preserve the day of the month. 284If it is impossible because the target month is shorter than the present one, 285the last day of the target month will be the result. 286For example, using 287.Fl v No +1m 288on May 31 will adjust the date to June 30, while using the same option 289on January 30 will result in the date adjusted to the last day of February. 290This approach is also believed to make the most sense for shell scripting. 291Nevertheless, be aware that going forth and back by the same number of 292months may take you to a different date. 293.Pp 294Refer to the examples below for further details. 295.El 296.Pp 297An operand with a leading plus 298.Pq Sq + 299sign signals a user-defined format string 300which specifies the format in which to display the date and time. 301The format string may contain any of the conversion specifications 302described in the 303.Xr strftime 3 304manual page, as well as any arbitrary text. 305A newline 306.Pq Ql \en 307character is always output after the characters specified by 308the format string. 309The format string for the default display is 310.Dq +%+ . 311.Pp 312If an operand does not have a leading plus sign, it is interpreted as 313a value for setting the system's notion of the current date and time. 314The canonical representation for setting the date and time is: 315.Pp 316.Bl -tag -width Ds -compact -offset indent 317.It Ar cc 318Century 319(either 19 or 20) 320prepended to the abbreviated year. 321.It Ar yy 322Year in abbreviated form 323(e.g., 89 for 1989, 06 for 2006). 324.It Ar mm 325Numeric month, a number from 1 to 12. 326.It Ar dd 327Day, a number from 1 to 31. 328.It Ar HH 329Hour, a number from 0 to 23. 330.It Ar MM 331Minutes, a number from 0 to 59. 332.It Ar ss 333Seconds, a number from 0 to 60 334(59 plus a potential leap second). 335.El 336.Pp 337Everything but the minutes is optional. 338.Pp 339Time changes for Daylight Saving Time, standard time, leap seconds, 340and leap years are handled automatically. 341.Sh ENVIRONMENT 342The following environment variables affect the execution of 343.Nm : 344.Bl -tag -width Ds 345.It Ev TZ 346The timezone to use when displaying dates. 347The normal format is a pathname relative to 348.Pa /usr/share/zoneinfo . 349For example, the command 350.Dq TZ=America/Los_Angeles date 351displays the current time in California. 352See 353.Xr environ 7 354for more information. 355.El 356.Sh FILES 357.Bl -tag -width /var/log/messages -compact 358.It Pa /var/log/utx.log 359record of date resets and time changes 360.It Pa /var/log/messages 361record of the user setting the time 362.El 363.Sh EXIT STATUS 364The 365.Nm 366utility exits 0 on success, 1 if unable to set the date, and 2 367if able to set the local date, but unable to set it globally. 368.Sh EXAMPLES 369The command: 370.Pp 371.Dl "date ""+DATE: %Y-%m-%d%nTIME: %H:%M:%S""" 372.Pp 373will display: 374.Bd -literal -offset indent 375DATE: 1987-11-21 376TIME: 13:36:16 377.Ed 378.Pp 379In the Europe/London timezone, the command: 380.Pp 381.Dl "date -v1m -v+1y" 382.Pp 383will display: 384.Pp 385.Dl "Sun Jan 4 04:15:24 GMT 1998" 386.Pp 387where it is currently 388.Li "Mon Aug 4 04:15:24 BST 1997" . 389.Pp 390The command: 391.Pp 392.Dl "date -v1d -v3m -v0y -v-1d" 393.Pp 394will display the last day of February in the year 2000: 395.Pp 396.Dl "Tue Feb 29 03:18:00 GMT 2000" 397.Pp 398So will the command: 399.Pp 400.Dl "date -v3m -v30d -v0y -v-1m" 401.Pp 402because there is no such date as the 30th of February. 403.Pp 404The command: 405.Pp 406.Dl "date -v1d -v+1m -v-1d -v-fri" 407.Pp 408will display the last Friday of the month: 409.Pp 410.Dl "Fri Aug 29 04:31:11 BST 1997" 411.Pp 412where it is currently 413.Li "Mon Aug 4 04:31:11 BST 1997" . 414.Pp 415The command: 416.Pp 417.Dl "date 8506131627" 418.Pp 419sets the date to 420.Dq Li "June 13, 1985, 4:27 PM" . 421.Pp 422.Dl "date ""+%Y%m%d%H%M.%S""" 423.Pp 424may be used on one machine to print out the date 425suitable for setting on another. 426.Qq ( Li "+%m%d%H%M%Y.%S" 427for use on 428.Tn Linux . ) 429.Pp 430The command: 431.Pp 432.Dl "date 1432" 433.Pp 434sets the time to 435.Li "2:32 PM" , 436without modifying the date. 437.Pp 438The command 439.Pp 440.Dl "TZ=America/Los_Angeles date -Iseconds -r 1533415339" 441.Pp 442will display 443.Pp 444.Dl "2018-08-04T13:42:19-07:00" 445.Pp 446Finally the command: 447.Pp 448.Dl "date -j -f ""%a %b %d %T %Z %Y"" ""`date`"" ""+%s""" 449.Pp 450can be used to parse the output from 451.Nm 452and express it in Epoch time. 453.Sh DIAGNOSTICS 454Occasionally, when 455.Xr timed 8 456synchronizes the time on many hosts, the setting of a new time value may 457require more than a few seconds. 458On these occasions, 459.Nm 460prints: 461.Ql Network time being set . 462The message 463.Ql Communication error with timed 464occurs when the communication 465between 466.Nm 467and 468.Xr timed 8 469fails. 470.Pp 471It is invalid to combine the 472.Fl I 473flag with either 474.Fl R 475or an output format 476.Dq ( + Ns ... ) 477operand. 478If this occurs, 479.Nm 480prints: 481.Ql multiple output formats specified 482and exits with an error status. 483.Sh SEE ALSO 484.Xr locale 1 , 485.Xr gettimeofday 2 , 486.Xr getutxent 3 , 487.Xr strftime 3 , 488.Xr strptime 3 , 489.Xr timed 8 490.Rs 491.%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD" 492.%A R. Gusella 493.%A S. Zatti 494.Re 495.Sh STANDARDS 496The 497.Nm 498utility is expected to be compatible with 499.St -p1003.2 . 500The 501.Fl d , f , I , j , n , r , t , 502and 503.Fl v 504options are all extensions to the standard. 505.Pp 506The format selected by the 507.Fl I 508flag is compatible with 509.St -iso8601 . 510.Sh HISTORY 511A 512.Nm 513command appeared in 514.At v1 . 515.Pp 516The 517.Fl I 518flag was added in 519.Fx 12.0 . 520