1.\" Copyright (c) 1980, 1990, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the Institute of Electrical and Electronics Engineers, Inc. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)date.1 8.3 (Berkeley) 4/28/95 32.\" $FreeBSD: src/bin/date/date.1,v 1.72 2005/02/13 22:25:09 ru Exp $ 33.\" 34.Dd February 16, 2022 35.Dt DATE 1 36.Os 37.Sh NAME 38.Nm date 39.Nd display or set date and time 40.Sh SYNOPSIS 41.Nm 42.Op Fl jRu 43.Op Fl r Ar seconds 44.Oo 45.Fl v 46.Sm off 47.Op Cm + | - 48.Ar val Op Ar ymwdHMS 49.Sm on 50.Oc 51.Ar ... 52.Op Cm + Ns Ar output_fmt 53.Nm 54.Op Fl jnRu 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 jnu 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 8 ) 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 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 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.Sq date . 117Valid 118.Ar FMT 119values are 120.Sq date , 121.Sq hours , 122.Sq minutes , 123and 124.Sq seconds . 125The date and time is formatted to the specified precision. 126The 127.St -iso8601 128format includes the timezone, except when 129.Ar FMT 130is 131.Sq date . 132.It Fl j 133Do not try to set the date. 134This allows you to use the 135.Fl f 136flag in addition to the 137.Cm + 138option to convert one date format to another. 139.It Fl n 140Obsolete flag, accepted and ignored for compatibility. 141.It Fl R 142Use RFC 2822 date and time output format. This is equivalent to use 143.Dq Li %a, %d %b %Y \&%T %z 144as 145.Ar output_fmt 146while 147.Ev LC_TIME 148is set to the 149.Dq C 150locale. 151.It Fl r Ar seconds 152Print the date and time represented by 153.Ar seconds , 154where 155.Ar seconds 156is the number of seconds since the Epoch 157(00:00:00 UTC, January 1, 1970; 158see 159.Xr time 3 ) , 160and can be specified in decimal, octal, or hex. 161.It Fl u 162Display or set the date in 163.Tn UTC 164(Coordinated Universal) time. 165.It Fl v 166Adjust (i.e., take the current date and display the result of the 167adjustment; not actually set the date) the second, minute, hour, month 168day, week day, month or year according to 169.Ar val . 170If 171.Ar val 172is preceded with a plus or minus sign, 173the date is adjusted forwards or backwards according to the remaining string, 174otherwise the relevant part of the date is set. 175The date can be adjusted as many times as required using these flags. 176Flags are processed in the order given. 177.Pp 178When setting values 179(rather than adjusting them), 180seconds are in the range 0-59, minutes are in the range 0-59, hours are 181in the range 0-23, month days are in the range 1-31, week days are in the 182range 0-6 (Sun-Sat), 183months are in the range 1-12 (Jan-Dec) 184and years are in the range 80-38 or 1980-2038. 185.Pp 186If 187.Ar val 188is numeric, one of either 189.Ar y , 190.Ar m , 191.Ar w , 192.Ar d , 193.Ar H , 194.Ar M 195or 196.Ar S 197must be used to specify which part of the date is to be adjusted. 198.Pp 199The week day or month may be specified using a name rather than a 200number. 201If a name is used with the plus 202(or minus) 203sign, the date will be put forwards 204(or backwards) 205to the next 206(previous) 207date that matches the given week day or month. 208This will not adjust the date, 209if the given week day or month is the same as the current one. 210.Pp 211When a date is adjusted to a specific value or in units greater than hours, 212daylight savings time considerations are ignored. 213Adjustments in units of hours or less honor daylight saving time. 214So, assuming the current date is March 26, 0:30 and that the DST adjustment 215means that the clock goes forward at 01:00 to 02:00, using 216.Fl v No +1H 217will adjust the date to March 26, 2:30. 218Likewise, if the date is October 29, 0:30 and the DST adjustment means that 219the clock goes back at 02:00 to 01:00, using 220.Fl v No +3H 221will be necessary to reach October 29, 2:30. 222.Pp 223When the date is adjusted to a specific value that does not actually exist 224(for example March 26, 1:30 BST 2000 in the Europe/London timezone), 225the date will be silently adjusted forwards in units of one hour until it 226reaches a valid time. 227When the date is adjusted to a specific value that occurs twice 228(for example October 29, 1:30 2000), 229the resulting timezone will be set so that the date matches the earlier of 230the two times. 231.Pp 232Adjusting the date by months is inherently ambiguous because 233a month is a unit of variable length depending on the current date. 234This kind of date adjustment is applied in the most intuitive way. 235First of all, 236.Nm 237tries to preserve the day of the month. 238If it is impossible because the target month is shorter than the present one, 239the last day of the target month will be the result. 240For example, using 241.Fl v No +1m 242on May 31 will adjust the date to June 30, while using the same option 243on January 30 will result in the date adjusted to the last day of February. 244This approach is also believed to make the most sense for shell scripting. 245Nevertheless, be aware that going forth and back by the same number of 246months may take you to a different date. 247.Pp 248Refer to the examples below for further details. 249.El 250.Pp 251An operand with a leading plus 252.Pq Sq + 253sign signals a user-defined format string 254which specifies the format in which to display the date and time. 255The format string may contain any of the conversion specifications 256described in the 257.Xr strftime 3 258manual page, as well as any arbitrary text. 259A newline 260.Pq Ql \en 261character is always output after the characters specified by 262the format string. 263The format string for the default display is 264.Dq +%+ . 265.Pp 266If an operand does not have a leading plus sign, it is interpreted as 267a value for setting the system's notion of the current date and time. 268The canonical representation for setting the date and time is: 269.Pp 270.Bl -tag -width Ds -compact -offset indent 271.It Ar cc 272Century 273(either 19 or 20) 274prepended to the abbreviated year. 275.It Ar yy 276Year in abbreviated form 277(e.g., 89 for 1989, 06 for 2006). 278.It Ar mm 279Numeric month, a number from 1 to 12. 280.It Ar dd 281Day, a number from 1 to 31. 282.It Ar HH 283Hour, a number from 0 to 23. 284.It Ar MM 285Minutes, a number from 0 to 59. 286.It Ar ss 287Seconds, a number from 0 to 61 288(59 plus a maximum of two leap seconds). 289.El 290.Pp 291Everything but the minutes is optional. 292.Pp 293Time changes for Daylight Saving Time, standard time, leap seconds, 294and leap years are handled automatically. 295.Sh ENVIRONMENT 296The following environment variables affect the execution of 297.Nm : 298.Bl -tag -width Ds 299.It Ev TZ 300The timezone to use when displaying dates. 301The normal format is a pathname relative to 302.Pa /usr/share/zoneinfo . 303For example, the command 304.Dq TZ=America/Los_Angeles date 305displays the current time in California. 306See 307.Xr environ 7 308for more information. 309.El 310.Sh FILES 311.Bl -tag -width /var/log/messages -compact 312.It Pa /var/log/wtmpx 313record of date resets and time changes 314.It Pa /var/log/messages 315record of the user setting the time 316.El 317.Sh EXIT STATUS 318The 319.Nm 320utility exits 0 on success, 1 if unable to set the date, and 2 321if able to set the local date, but unable to set it globally. 322.Sh EXAMPLES 323The command: 324.Pp 325.Dl "date ""+DATE: %Y-%m-%d%nTIME: %H:%M:%S""" 326.Pp 327will display: 328.Bd -literal -offset indent 329DATE: 1987-11-21 330TIME: 13:36:16 331.Ed 332.Pp 333In the Europe/London timezone, the command: 334.Pp 335.Dl "date -v1m -v+1y" 336.Pp 337will display: 338.Pp 339.Dl "Sun Jan 4 04:15:24 GMT 1998" 340.Pp 341where it is currently 342.Li "Mon Aug 4 04:15:24 BST 1997" . 343.Pp 344The command: 345.Pp 346.Dl "date -v1d -v3m -v0y -v-1d" 347.Pp 348will display the last day of February in the year 2000: 349.Pp 350.Dl "Tue Feb 29 03:18:00 GMT 2000" 351.Pp 352So will do the command: 353.Pp 354.Dl "date -v30d -v3m -v0y -v-1m" 355.Pp 356because there is no such date as the 30th of February. 357.Pp 358The command: 359.Pp 360.Dl "date -v1d -v+1m -v-1d -v-fri" 361.Pp 362will display the last Friday of the month: 363.Pp 364.Dl "Fri Aug 29 04:31:11 BST 1997" 365.Pp 366where it is currently 367.Li "Mon Aug 4 04:31:11 BST 1997" . 368.Pp 369The command: 370.Pp 371.Dl "date 8506131627" 372.Pp 373sets the date to 374.Dq Li "June 13, 1985, 4:27 PM" . 375.Pp 376.Dl "date ""+%Y%m%d%H%M.%S""" 377.Pp 378may be used on one machine to print out the date 379suitable for setting on another. 380.Qq ( Li "+%m%d%H%M%Y.%S" 381for use on 382.Tn Linux . ) 383.Pp 384The command: 385.Pp 386.Dl "date 1432" 387.Pp 388sets the time to 389.Li "2:32 PM" , 390without modifying the date. 391.Pp 392The command: 393.Pp 394.Dl "TZ=America/Los_Angeles date -Iseconds -r 1533415339" 395.Pp 396will display 397.Pp 398.Dl "2018-08-04T13:42:19-07:00" 399.Pp 400Finally the command: 401.Pp 402.Dl "date -j -f ""%a %b %d %T %Z %Y"" ""`date`"" ""+%s""" 403.Pp 404can be used to parse the output from 405.Nm 406and express it in Epoch time. 407.Sh SEE ALSO 408.Xr gettimeofday 2 , 409.Xr strftime 3 , 410.Xr strptime 3 , 411.Xr utmpx 5 412.Sh STANDARDS 413The 414.Nm 415utility is expected to be compatible with 416.St -p1003.2 . 417.Pp 418The format selected by the 419.Fl I 420flag is compatible with 421.St -iso8601 . 422.Sh HISTORY 423A 424.Nm 425command appeared in 426.At v1 . 427.Pp 428The 429.Fl I 430flag was added in 431.Fx 12.0 432and 433.Dx 6.3 . 434