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 April 23, 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 jnRu 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 n 146Obsolete flag, accepted and ignored for compatibility. 147.It Fl R 148Use RFC 2822 date and time output format. 149This is equivalent to using 150.Dq Li %a, %d %b %Y \&%T %z 151as 152.Ar output_fmt 153while 154.Ev LC_TIME 155is set to the 156.Dq C 157locale . 158.It Fl r Ar seconds 159Print the date and time represented by 160.Ar seconds , 161where 162.Ar seconds 163is the number of seconds since the Epoch 164(00:00:00 UTC, January 1, 1970; 165see 166.Xr time 3 ) , 167and can be specified in decimal, octal, or hex. 168.It Fl r Ar filename 169Print the date and time of the last modification of 170.Ar filename . 171.It Fl u 172Display or set the date in 173.Tn UTC 174(Coordinated Universal) time. 175.It Fl v 176Adjust (i.e., take the current date and display the result of the 177adjustment; not actually set the date) the second, minute, hour, month 178day, week day, month or year according to 179.Ar val . 180If 181.Ar val 182is preceded with a plus or minus sign, 183the date is adjusted forwards or backwards according to the remaining string, 184otherwise the relevant part of the date is set. 185The date can be adjusted as many times as required using these flags. 186Flags are processed in the order given. 187.Pp 188When setting values 189(rather than adjusting them), 190seconds are in the range 0-59, minutes are in the range 0-59, hours are 191in the range 0-23, month days are in the range 1-31, week days are in the 192range 0-6 (Sun-Sat), 193months are in the range 1-12 (Jan-Dec) 194and years are in the range 80-38 or 1980-2038. 195.Pp 196If 197.Ar val 198is numeric, one of either 199.Ar y , 200.Ar m , 201.Ar w , 202.Ar d , 203.Ar H , 204.Ar M 205or 206.Ar S 207must be used to specify which part of the date is to be adjusted. 208.Pp 209The week day or month may be specified using a name rather than a 210number. 211If a name is used with the plus 212(or minus) 213sign, the date will be put forwards 214(or backwards) 215to the next 216(previous) 217date that matches the given week day or month. 218This will not adjust the date, 219if the given week day or month is the same as the current one. 220.Pp 221When a date is adjusted to a specific value or in units greater than hours, 222daylight savings time considerations are ignored. 223Adjustments in units of hours or less honor daylight saving time. 224So, assuming the current date is March 26, 0:30 and that the DST adjustment 225means that the clock goes forward at 01:00 to 02:00, using 226.Fl v No +1H 227will adjust the date to March 26, 2:30. 228Likewise, if the date is October 29, 0:30 and the DST adjustment means that 229the clock goes back at 02:00 to 01:00, using 230.Fl v No +3H 231will be necessary to reach October 29, 2:30. 232.Pp 233When 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), 235the date will be silently adjusted forwards in units of one hour until it 236reaches a valid time. 237When the date is adjusted to a specific value that occurs twice 238(for example October 29, 1:30 2000), 239the resulting timezone will be set so that the date matches the earlier of 240the two times. 241.Pp 242It is not possible to adjust a date to an invalid absolute day, so using 243the switches 244.Fl v No 31d Fl v No 12m 245will simply fail five months of the year. 246It is therefore usual to set the month before setting the day; using 247.Fl v No 12m Fl v No 31d 248always works. 249.Pp 250Adjusting the date by months is inherently ambiguous because 251a month is a unit of variable length depending on the current date. 252This kind of date adjustment is applied in the most intuitive way. 253First of all, 254.Nm 255tries to preserve the day of the month. 256If it is impossible because the target month is shorter than the present one, 257the last day of the target month will be the result. 258For example, using 259.Fl v No +1m 260on May 31 will adjust the date to June 30, while using the same option 261on January 30 will result in the date adjusted to the last day of February. 262This approach is also believed to make the most sense for shell scripting. 263Nevertheless, be aware that going forth and back by the same number of 264months may take you to a different date. 265.Pp 266Refer to the examples below for further details. 267.El 268.Pp 269An operand with a leading plus 270.Pq Sq + 271sign signals a user-defined format string 272which specifies the format in which to display the date and time. 273The format string may contain any of the conversion specifications 274described in the 275.Xr strftime 3 276manual page, as well as any arbitrary text. 277A newline 278.Pq Ql \en 279character is always output after the characters specified by 280the format string. 281The format string for the default display is 282.Dq +%+ . 283.Pp 284If an operand does not have a leading plus sign, it is interpreted as 285a value for setting the system's notion of the current date and time. 286The canonical representation for setting the date and time is: 287.Pp 288.Bl -tag -width Ds -compact -offset indent 289.It Ar cc 290Century 291(either 19 or 20) 292prepended to the abbreviated year. 293.It Ar yy 294Year in abbreviated form 295(e.g., 89 for 1989, 06 for 2006). 296.It Ar mm 297Numeric month, a number from 1 to 12. 298.It Ar dd 299Day, a number from 1 to 31. 300.It Ar HH 301Hour, a number from 0 to 23. 302.It Ar MM 303Minutes, a number from 0 to 59. 304.It Ar ss 305Seconds, a number from 0 to 60 306(59 plus a potential leap second). 307.El 308.Pp 309Everything but the minutes is optional. 310.Pp 311Time changes for Daylight Saving Time, standard time, leap seconds, 312and leap years are handled automatically. 313.Sh ENVIRONMENT 314The following environment variables affect the execution of 315.Nm : 316.Bl -tag -width Ds 317.It Ev TZ 318The timezone to use when displaying dates. 319The normal format is a pathname relative to 320.Pa /usr/share/zoneinfo . 321For example, the command 322.Dq TZ=America/Los_Angeles date 323displays the current time in California. 324See 325.Xr environ 7 326for more information. 327.El 328.Sh FILES 329.Bl -tag -width /var/log/messages -compact 330.It Pa /var/log/utx.log 331record of date resets and time changes 332.It Pa /var/log/messages 333record of the user setting the time 334.El 335.Sh EXIT STATUS 336The 337.Nm 338utility exits 0 on success, 1 if unable to set the date, and 2 339if able to set the local date, but unable to set it globally. 340.Sh EXAMPLES 341The command: 342.Pp 343.Dl "date ""+DATE: %Y-%m-%d%nTIME: %H:%M:%S""" 344.Pp 345will display: 346.Bd -literal -offset indent 347DATE: 1987-11-21 348TIME: 13:36:16 349.Ed 350.Pp 351In the Europe/London timezone, the command: 352.Pp 353.Dl "date -v1m -v+1y" 354.Pp 355will display: 356.Pp 357.Dl "Sun Jan 4 04:15:24 GMT 1998" 358.Pp 359where it is currently 360.Li "Mon Aug 4 04:15:24 BST 1997" . 361.Pp 362The command: 363.Pp 364.Dl "date -v1d -v3m -v0y -v-1d" 365.Pp 366will display the last day of February in the year 2000: 367.Pp 368.Dl "Tue Feb 29 03:18:00 GMT 2000" 369.Pp 370So will the command: 371.Pp 372.Dl "date -v3m -v30d -v0y -v-1m" 373.Pp 374because there is no such date as the 30th of February. 375.Pp 376The command: 377.Pp 378.Dl "date -v1d -v+1m -v-1d -v-fri" 379.Pp 380will display the last Friday of the month: 381.Pp 382.Dl "Fri Aug 29 04:31:11 BST 1997" 383.Pp 384where it is currently 385.Li "Mon Aug 4 04:31:11 BST 1997" . 386.Pp 387The command: 388.Pp 389.Dl "date 8506131627" 390.Pp 391sets the date to 392.Dq Li "June 13, 1985, 4:27 PM" . 393.Pp 394.Dl "date ""+%Y%m%d%H%M.%S""" 395.Pp 396may be used on one machine to print out the date 397suitable for setting on another. 398.Qq ( Li "+%m%d%H%M%Y.%S" 399for use on 400.Tn Linux . ) 401.Pp 402The command: 403.Pp 404.Dl "date 1432" 405.Pp 406sets the time to 407.Li "2:32 PM" , 408without modifying the date. 409.Pp 410The command 411.Pp 412.Dl "TZ=America/Los_Angeles date -Iseconds -r 1533415339" 413.Pp 414will display 415.Pp 416.Dl "2018-08-04T13:42:19-07:00" 417.Pp 418Finally the command: 419.Pp 420.Dl "date -j -f ""%a %b %d %T %Z %Y"" ""`date`"" ""+%s""" 421.Pp 422can be used to parse the output from 423.Nm 424and express it in Epoch time. 425.Sh DIAGNOSTICS 426It is invalid to combine the 427.Fl I 428flag with either 429.Fl R 430or an output format 431.Dq ( + Ns ... ) 432operand. 433If this occurs, 434.Nm 435prints: 436.Ql multiple output formats specified 437and exits with an error status. 438.Sh SEE ALSO 439.Xr locale 1 , 440.Xr gettimeofday 2 , 441.Xr getutxent 3 , 442.Xr strftime 3 , 443.Xr strptime 3 444.Rs 445.%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD" 446.%A R. Gusella 447.%A S. Zatti 448.Re 449.Sh STANDARDS 450The 451.Nm 452utility is expected to be compatible with 453.St -p1003.2 . 454The 455.Fl d , f , I , j , r , t , 456and 457.Fl v 458options are all extensions to the standard. 459.Pp 460The format selected by the 461.Fl I 462flag is compatible with 463.St -iso8601 . 464.Sh HISTORY 465A 466.Nm 467command appeared in 468.At v1 . 469.Pp 470The 471.Fl I 472flag was added in 473.Fx 12.0 . 474