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 March 20, 2019 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 ju 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 jRu 62.Fl f Ar input_fmt new_date 63.Op Cm + Ns Ar output_fmt 64.Nm 65.Op Fl jnu 66.Op Fl I Ns Op Ar FMT 67.Op Fl f Ar input_fmt 68.Op Fl r Ar ... 69.Op Fl v Ar ... 70.Op Ar new_date 71.Sh DESCRIPTION 72When invoked without arguments, the 73.Nm 74utility displays the current date and time. 75Otherwise, depending on the options specified, 76.Nm 77will set the date and time or print it in a user-defined way. 78.Pp 79The 80.Nm 81utility displays the date and time read from the kernel clock. 82When used to set the date and time, 83both the kernel clock and the hardware clock are updated. 84.Pp 85Only the superuser may set the date, 86and if the system securelevel (see 87.Xr securelevel 7 ) 88is greater than 1, 89the time may not be changed by more than 1 second. 90.Pp 91The options are as follows: 92.Bl -tag -width Ds 93.It Fl f 94Use 95.Ar input_fmt 96as the format string to parse the 97.Ar new_date 98provided rather than using the default 99.Sm off 100.Oo Oo Oo Oo Oo 101.Ar cc Oc 102.Ar yy Oc 103.Ar mm Oc 104.Ar dd Oc 105.Ar HH 106.Oc Ar MM Op Ar .ss 107.Sm on 108format. 109Parsing is done using 110.Xr strptime 3 . 111.It Fl I Ns Op Ar FMT 112Use 113.St -iso8601 114output format. 115.Ar FMT 116may be omitted, in which case the default is 117.Sq date . 118Valid 119.Ar FMT 120values are 121.Sq date , 122.Sq hours , 123.Sq minutes , 124and 125.Sq seconds . 126The date and time is formatted to the specified precision. 127When 128.Ar FMT 129is 130.Sq hours 131(or the more precise 132.Sq minutes 133or 134.Sq seconds ) , 135the 136.St -iso8601 137format includes the timezone. 138.It Fl j 139Do not try to set the date. 140This allows you to use the 141.Fl f 142flag in addition to the 143.Cm + 144option to convert one date format to another. 145.It Fl R 146Use RFC 2822 date and time output format. 147This is equivalent to using 148.Dq Li %a, %d %b %Y \&%T %z 149as 150.Ar output_fmt 151while 152.Ev LC_TIME 153is set to the 154.Dq C 155locale . 156.It Fl r Ar seconds 157Print the date and time represented by 158.Ar seconds , 159where 160.Ar seconds 161is the number of seconds since the Epoch 162(00:00:00 UTC, January 1, 1970; 163see 164.Xr time 3 ) , 165and can be specified in decimal, octal, or hex. 166.It Fl r Ar filename 167Print the date and time of the last modification of 168.Ar filename . 169.It Fl u 170Display or set the date in 171.Tn UTC 172(Coordinated Universal) time. 173.It Fl v 174Adjust (i.e., take the current date and display the result of the 175adjustment; not actually set the date) the second, minute, hour, month 176day, week day, month or year according to 177.Ar val . 178If 179.Ar val 180is preceded with a plus or minus sign, 181the date is adjusted forwards or backwards according to the remaining string, 182otherwise the relevant part of the date is set. 183The date can be adjusted as many times as required using these flags. 184Flags are processed in the order given. 185.Pp 186When setting values 187(rather than adjusting them), 188seconds are in the range 0-59, minutes are in the range 0-59, hours are 189in the range 0-23, month days are in the range 1-31, week days are in the 190range 0-6 (Sun-Sat), 191months are in the range 1-12 (Jan-Dec) 192and years are in the range 80-38 or 1980-2038. 193.Pp 194If 195.Ar val 196is numeric, one of either 197.Ar y , 198.Ar m , 199.Ar w , 200.Ar d , 201.Ar H , 202.Ar M 203or 204.Ar S 205must be used to specify which part of the date is to be adjusted. 206.Pp 207The week day or month may be specified using a name rather than a 208number. 209If a name is used with the plus 210(or minus) 211sign, the date will be put forwards 212(or backwards) 213to the next 214(previous) 215date that matches the given week day or month. 216This will not adjust the date, 217if the given week day or month is the same as the current one. 218.Pp 219When a date is adjusted to a specific value or in units greater than hours, 220daylight savings time considerations are ignored. 221Adjustments in units of hours or less honor daylight saving time. 222So, assuming the current date is March 26, 0:30 and that the DST adjustment 223means that the clock goes forward at 01:00 to 02:00, using 224.Fl v No +1H 225will adjust the date to March 26, 2:30. 226Likewise, if the date is October 29, 0:30 and the DST adjustment means that 227the clock goes back at 02:00 to 01:00, using 228.Fl v No +3H 229will be necessary to reach October 29, 2:30. 230.Pp 231When the date is adjusted to a specific value that does not actually exist 232(for example March 26, 1:30 BST 2000 in the Europe/London timezone), 233the date will be silently adjusted forwards in units of one hour until it 234reaches a valid time. 235When the date is adjusted to a specific value that occurs twice 236(for example October 29, 1:30 2000), 237the resulting timezone will be set so that the date matches the earlier of 238the two times. 239.Pp 240It is not possible to adjust a date to an invalid absolute day, so using 241the switches 242.Fl v No 31d Fl v No 12m 243will simply fail five months of the year. 244It is therefore usual to set the month before setting the day; using 245.Fl v No 12m Fl v No 31d 246always works. 247.Pp 248Adjusting the date by months is inherently ambiguous because 249a month is a unit of variable length depending on the current date. 250This kind of date adjustment is applied in the most intuitive way. 251First of all, 252.Nm 253tries to preserve the day of the month. 254If it is impossible because the target month is shorter than the present one, 255the last day of the target month will be the result. 256For example, using 257.Fl v No +1m 258on May 31 will adjust the date to June 30, while using the same option 259on January 30 will result in the date adjusted to the last day of February. 260This approach is also believed to make the most sense for shell scripting. 261Nevertheless, be aware that going forth and back by the same number of 262months may take you to a different date. 263.Pp 264Refer to the examples below for further details. 265.El 266.Pp 267An operand with a leading plus 268.Pq Sq + 269sign signals a user-defined format string 270which specifies the format in which to display the date and time. 271The format string may contain any of the conversion specifications 272described in the 273.Xr strftime 3 274manual page, as well as any arbitrary text. 275A newline 276.Pq Ql \en 277character is always output after the characters specified by 278the format string. 279The format string for the default display is 280.Dq +%+ . 281.Pp 282If an operand does not have a leading plus sign, it is interpreted as 283a value for setting the system's notion of the current date and time. 284The canonical representation for setting the date and time is: 285.Pp 286.Bl -tag -width Ds -compact -offset indent 287.It Ar cc 288Century 289(either 19 or 20) 290prepended to the abbreviated year. 291.It Ar yy 292Year in abbreviated form 293(e.g., 89 for 1989, 06 for 2006). 294.It Ar mm 295Numeric month, a number from 1 to 12. 296.It Ar dd 297Day, a number from 1 to 31. 298.It Ar HH 299Hour, a number from 0 to 23. 300.It Ar MM 301Minutes, a number from 0 to 59. 302.It Ar ss 303Seconds, a number from 0 to 60 304(59 plus a potential leap second). 305.El 306.Pp 307Everything but the minutes is optional. 308.Pp 309Time changes for Daylight Saving Time, standard time, leap seconds, 310and leap years are handled automatically. 311.Sh ENVIRONMENT 312The following environment variables affect the execution of 313.Nm : 314.Bl -tag -width Ds 315.It Ev TZ 316The timezone to use when displaying dates. 317The normal format is a pathname relative to 318.Pa /usr/share/zoneinfo . 319For example, the command 320.Dq TZ=America/Los_Angeles date 321displays the current time in California. 322See 323.Xr environ 7 324for more information. 325.El 326.Sh FILES 327.Bl -tag -width /var/log/messages -compact 328.It Pa /var/log/utx.log 329record of date resets and time changes 330.It Pa /var/log/messages 331record of the user setting the time 332.El 333.Sh EXIT STATUS 334The 335.Nm 336utility exits 0 on success, 1 if unable to set the date, and 2 337if able to set the local date, but unable to set it globally. 338.Sh EXAMPLES 339The command: 340.Pp 341.Dl "date ""+DATE: %Y-%m-%d%nTIME: %H:%M:%S""" 342.Pp 343will display: 344.Bd -literal -offset indent 345DATE: 1987-11-21 346TIME: 13:36:16 347.Ed 348.Pp 349In the Europe/London timezone, the command: 350.Pp 351.Dl "date -v1m -v+1y" 352.Pp 353will display: 354.Pp 355.Dl "Sun Jan 4 04:15:24 GMT 1998" 356.Pp 357where it is currently 358.Li "Mon Aug 4 04:15:24 BST 1997" . 359.Pp 360The command: 361.Pp 362.Dl "date -v1d -v3m -v0y -v-1d" 363.Pp 364will display the last day of February in the year 2000: 365.Pp 366.Dl "Tue Feb 29 03:18:00 GMT 2000" 367.Pp 368So will the command: 369.Pp 370.Dl "date -v3m -v30d -v0y -v-1m" 371.Pp 372because there is no such date as the 30th of February. 373.Pp 374The command: 375.Pp 376.Dl "date -v1d -v+1m -v-1d -v-fri" 377.Pp 378will display the last Friday of the month: 379.Pp 380.Dl "Fri Aug 29 04:31:11 BST 1997" 381.Pp 382where it is currently 383.Li "Mon Aug 4 04:31:11 BST 1997" . 384.Pp 385The command: 386.Pp 387.Dl "date 8506131627" 388.Pp 389sets the date to 390.Dq Li "June 13, 1985, 4:27 PM" . 391.Pp 392.Dl "date ""+%Y%m%d%H%M.%S""" 393.Pp 394may be used on one machine to print out the date 395suitable for setting on another. 396.Qq ( Li "+%m%d%H%M%Y.%S" 397for use on 398.Tn Linux . ) 399.Pp 400The command: 401.Pp 402.Dl "date 1432" 403.Pp 404sets the time to 405.Li "2:32 PM" , 406without modifying the date. 407.Pp 408The command 409.Pp 410.Dl "TZ=America/Los_Angeles date -Iseconds -r 1533415339" 411.Pp 412will display 413.Pp 414.Dl "2018-08-04T13:42:19-07:00" 415.Pp 416Finally the command: 417.Pp 418.Dl "date -j -f ""%a %b %d %T %Z %Y"" ""`date`"" ""+%s""" 419.Pp 420can be used to parse the output from 421.Nm 422and express it in Epoch time. 423.Sh DIAGNOSTICS 424It is invalid to combine the 425.Fl I 426flag with either 427.Fl R 428or an output format 429.Dq ( + Ns ... ) 430operand. 431If this occurs, 432.Nm 433prints: 434.Ql multiple output formats specified 435and exits with an error status. 436.Sh SEE ALSO 437.Xr locale 1 , 438.Xr gettimeofday 2 , 439.Xr getutxent 3 , 440.Xr strftime 3 , 441.Xr strptime 3 442.Rs 443.%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD" 444.%A R. Gusella 445.%A S. Zatti 446.Re 447.Sh STANDARDS 448The 449.Nm 450utility is expected to be compatible with 451.St -p1003.2 . 452The 453.Fl d , f , I , j , r , t , 454and 455.Fl v 456options are all extensions to the standard. 457.Pp 458The format selected by the 459.Fl I 460flag is compatible with 461.St -iso8601 . 462.Sh HISTORY 463A 464.Nm 465command appeared in 466.At v1 . 467.Pp 468The 469.Fl I 470flag was added in 471.Fx 12.0 . 472