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 June 16, 2021 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. 145Note that any date or time components unspecified by the 146.Fl f 147format string take their values from the current time. 148.It Fl n 149Obsolete flag, accepted and ignored for compatibility. 150.It Fl R 151Use RFC 2822 date and time output format. 152This is equivalent to using 153.Dq Li %a, %d %b %Y \&%T %z 154as 155.Ar output_fmt 156while 157.Ev LC_TIME 158is set to the 159.Dq C 160locale . 161.It Fl r Ar seconds 162Print the date and time represented by 163.Ar seconds , 164where 165.Ar seconds 166is the number of seconds since the Epoch 167(00:00:00 UTC, January 1, 1970; 168see 169.Xr time 3 ) , 170and can be specified in decimal, octal, or hex. 171.It Fl r Ar filename 172Print the date and time of the last modification of 173.Ar filename . 174.It Fl u 175Display or set the date in 176.Tn UTC 177(Coordinated Universal) time. 178.It Fl v 179Adjust (i.e., take the current date and display the result of the 180adjustment; not actually set the date) the second, minute, hour, month 181day, week day, month or year according to 182.Ar val . 183If 184.Ar val 185is preceded with a plus or minus sign, 186the date is adjusted forwards or backwards according to the remaining string, 187otherwise the relevant part of the date is set. 188The date can be adjusted as many times as required using these flags. 189Flags are processed in the order given. 190.Pp 191When setting values 192(rather than adjusting them), 193seconds are in the range 0-59, minutes are in the range 0-59, hours are 194in the range 0-23, month days are in the range 1-31, week days are in the 195range 0-6 (Sun-Sat), 196months are in the range 1-12 (Jan-Dec) 197and years are in the range 80-38 or 1980-2038. 198.Pp 199If 200.Ar val 201is numeric, one of either 202.Ar y , 203.Ar m , 204.Ar w , 205.Ar d , 206.Ar H , 207.Ar M 208or 209.Ar S 210must be used to specify which part of the date is to be adjusted. 211.Pp 212The week day or month may be specified using a name rather than a 213number. 214If a name is used with the plus 215(or minus) 216sign, the date will be put forwards 217(or backwards) 218to the next 219(previous) 220date that matches the given week day or month. 221This will not adjust the date, 222if the given week day or month is the same as the current one. 223.Pp 224When a date is adjusted to a specific value or in units greater than hours, 225daylight savings time considerations are ignored. 226Adjustments in units of hours or less honor daylight saving time. 227So, assuming the current date is March 26, 0:30 and that the DST adjustment 228means that the clock goes forward at 01:00 to 02:00, using 229.Fl v No +1H 230will adjust the date to March 26, 2:30. 231Likewise, if the date is October 29, 0:30 and the DST adjustment means that 232the clock goes back at 02:00 to 01:00, using 233.Fl v No +3H 234will be necessary to reach October 29, 2:30. 235.Pp 236When the date is adjusted to a specific value that does not actually exist 237(for example March 26, 1:30 BST 2000 in the Europe/London timezone), 238the date will be silently adjusted forwards in units of one hour until it 239reaches a valid time. 240When the date is adjusted to a specific value that occurs twice 241(for example October 29, 1:30 2000), 242the resulting timezone will be set so that the date matches the earlier of 243the two times. 244.Pp 245It is not possible to adjust a date to an invalid absolute day, so using 246the switches 247.Fl v No 31d Fl v No 12m 248will simply fail five months of the year. 249It is therefore usual to set the month before setting the day; using 250.Fl v No 12m Fl v No 31d 251always works. 252.Pp 253Adjusting the date by months is inherently ambiguous because 254a month is a unit of variable length depending on the current date. 255This kind of date adjustment is applied in the most intuitive way. 256First of all, 257.Nm 258tries to preserve the day of the month. 259If it is impossible because the target month is shorter than the present one, 260the last day of the target month will be the result. 261For example, using 262.Fl v No +1m 263on May 31 will adjust the date to June 30, while using the same option 264on January 30 will result in the date adjusted to the last day of February. 265This approach is also believed to make the most sense for shell scripting. 266Nevertheless, be aware that going forth and back by the same number of 267months may take you to a different date. 268.Pp 269Refer to the examples below for further details. 270.El 271.Pp 272An operand with a leading plus 273.Pq Sq + 274sign signals a user-defined format string 275which specifies the format in which to display the date and time. 276The format string may contain any of the conversion specifications 277described in the 278.Xr strftime 3 279manual page, as well as any arbitrary text. 280A newline 281.Pq Ql \en 282character is always output after the characters specified by 283the format string. 284The format string for the default display is 285.Dq +%+ . 286.Pp 287If an operand does not have a leading plus sign, it is interpreted as 288a value for setting the system's notion of the current date and time. 289The canonical representation for setting the date and time is: 290.Pp 291.Bl -tag -width Ds -compact -offset indent 292.It Ar cc 293Century 294(either 19 or 20) 295prepended to the abbreviated year. 296.It Ar yy 297Year in abbreviated form 298(e.g., 89 for 1989, 06 for 2006). 299.It Ar mm 300Numeric month, a number from 1 to 12. 301.It Ar dd 302Day, a number from 1 to 31. 303.It Ar HH 304Hour, a number from 0 to 23. 305.It Ar MM 306Minutes, a number from 0 to 59. 307.It Ar ss 308Seconds, a number from 0 to 60 309(59 plus a potential leap second). 310.El 311.Pp 312Everything but the minutes is optional. 313.Pp 314Time changes for Daylight Saving Time, standard time, leap seconds, 315and leap years are handled automatically. 316.Sh ENVIRONMENT 317The following environment variables affect the execution of 318.Nm : 319.Bl -tag -width Ds 320.It Ev TZ 321The timezone to use when displaying dates. 322The normal format is a pathname relative to 323.Pa /usr/share/zoneinfo . 324For example, the command 325.Dq TZ=America/Los_Angeles date 326displays the current time in California. 327See 328.Xr environ 7 329for more information. 330.El 331.Sh FILES 332.Bl -tag -width /var/log/messages -compact 333.It Pa /var/log/utx.log 334record of date resets and time changes 335.It Pa /var/log/messages 336record of the user setting the time 337.El 338.Sh EXIT STATUS 339The 340.Nm 341utility exits 0 on success, 1 if unable to set the date, and 2 342if able to set the local date, but unable to set it globally. 343.Sh EXAMPLES 344The command: 345.Pp 346.Dl "date ""+DATE: %Y-%m-%d%nTIME: %H:%M:%S""" 347.Pp 348will display: 349.Bd -literal -offset indent 350DATE: 1987-11-21 351TIME: 13:36:16 352.Ed 353.Pp 354In the Europe/London timezone, the command: 355.Pp 356.Dl "date -v1m -v+1y" 357.Pp 358will display: 359.Pp 360.Dl "Sun Jan 4 04:15:24 GMT 1998" 361.Pp 362where it is currently 363.Li "Mon Aug 4 04:15:24 BST 1997" . 364.Pp 365The command: 366.Pp 367.Dl "date -v1d -v3m -v0y -v-1d" 368.Pp 369will display the last day of February in the year 2000: 370.Pp 371.Dl "Tue Feb 29 03:18:00 GMT 2000" 372.Pp 373So will the command: 374.Pp 375.Dl "date -v3m -v30d -v0y -v-1m" 376.Pp 377because there is no such date as the 30th of February. 378.Pp 379The command: 380.Pp 381.Dl "date -v1d -v+1m -v-1d -v-fri" 382.Pp 383will display the last Friday of the month: 384.Pp 385.Dl "Fri Aug 29 04:31:11 BST 1997" 386.Pp 387where it is currently 388.Li "Mon Aug 4 04:31:11 BST 1997" . 389.Pp 390The command: 391.Pp 392.Dl "date 8506131627" 393.Pp 394sets the date to 395.Dq Li "June 13, 1985, 4:27 PM" . 396.Pp 397.Dl "date ""+%Y%m%d%H%M.%S""" 398.Pp 399may be used on one machine to print out the date 400suitable for setting on another. 401.Qq ( Li "+%m%d%H%M%Y.%S" 402for use on 403.Tn Linux . ) 404.Pp 405The command: 406.Pp 407.Dl "date 1432" 408.Pp 409sets the time to 410.Li "2:32 PM" , 411without modifying the date. 412.Pp 413The command 414.Pp 415.Dl "TZ=America/Los_Angeles date -Iseconds -r 1533415339" 416.Pp 417will display 418.Pp 419.Dl "2018-08-04T13:42:19-07:00" 420.Pp 421Finally the command: 422.Pp 423.Dl "date -j -f ""%a %b %d %T %Z %Y"" ""`date`"" ""+%s""" 424.Pp 425can be used to parse the output from 426.Nm 427and express it in Epoch time. 428.Sh DIAGNOSTICS 429It is invalid to combine the 430.Fl I 431flag with either 432.Fl R 433or an output format 434.Dq ( + Ns ... ) 435operand. 436If this occurs, 437.Nm 438prints: 439.Ql multiple output formats specified 440and exits with an error status. 441.Sh SEE ALSO 442.Xr locale 1 , 443.Xr gettimeofday 2 , 444.Xr getutxent 3 , 445.Xr strftime 3 , 446.Xr strptime 3 447.Rs 448.%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD" 449.%A R. Gusella 450.%A S. Zatti 451.Re 452.Sh STANDARDS 453The 454.Nm 455utility is expected to be compatible with 456.St -p1003.2 . 457The 458.Fl f , I , j , r , 459and 460.Fl v 461options are all extensions to the standard. 462.Pp 463The format selected by the 464.Fl I 465flag is compatible with 466.St -iso8601 . 467.Sh HISTORY 468A 469.Nm 470command appeared in 471.At v1 . 472.Pp 473The 474.Fl I 475flag was added in 476.Fx 12.0 . 477