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