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.\" Display time. 43.Nm 44.Op Fl nRu 45.Op Fl I Ns Op Ar FMT 46.Op Fl r Ar filename 47.Op Fl r Ar seconds 48.Oo 49.Sm off 50.Fl v 51.Op Cm + | - 52.Ar val Op Cm y | m | w | d | H | M | S 53.Sm on 54.Oc 55.Op Cm + Ns Ar output_fmt 56.\" Set time with the default input format. 57.Nm 58.Op Fl jnRu 59.Op Fl I Ns Op Ar FMT 60.Oo 61.Sm off 62.Fl v 63.Op Cm + | - 64.Ar val Op Cm y | m | w | d | H | M | S 65.Sm on 66.Oc 67.Sm off 68.Oo Oo Oo Oo Oo 69.Ar cc Oc 70.Ar yy Oc 71.Ar mm Oc 72.Ar dd Oc 73.Ar HH 74.Oc Ar MM Op Cm \&. Ar SS 75.Sm on 76.Op Cm + Ns Ar output_fmt 77.\" Set time with the user-provided input format. 78.Nm 79.Op Fl jnRu 80.Op Fl I Ns Op Ar FMT 81.Oo 82.Sm off 83.Fl v 84.Op Cm + | - 85.Ar val Op Cm y | m | w | d | H | M | S 86.Sm on 87.Oc 88.Fl f Ar input_fmt 89.Ar new_date 90.Op Cm + Ns Ar output_fmt 91.Sh DESCRIPTION 92When invoked without arguments, the 93.Nm 94utility displays the current date and time. 95Otherwise, depending on the options specified, 96.Nm 97will set the date and time or print it in a user-defined way. 98.Pp 99The 100.Nm 101utility displays the date and time read from the kernel clock. 102When used to set the date and time, 103both the kernel clock and the hardware clock are updated. 104.Pp 105Only the superuser may set the date, 106and if the system securelevel (see 107.Xr securelevel 7 ) 108is greater than 1, 109the time may not be changed by more than 1 second. 110.Pp 111The options are as follows: 112.Bl -tag -width Ds 113.It Fl f Ar input_fmt 114Use 115.Ar input_fmt 116as the format string to parse the 117.Ar new_date 118provided rather than using the default 119.Sm off 120.Oo Oo Oo Oo Oo 121.Ar cc Oc 122.Ar yy Oc 123.Ar mm Oc 124.Ar dd Oc 125.Ar HH 126.Oc Ar MM Op Cm \&. Ar SS 127.Sm on 128format. 129Parsing is done using 130.Xr strptime 3 . 131.It Fl I Ns Op Ar FMT 132Use 133.St -iso8601 134output format. 135.Ar FMT 136may be omitted, in which case the default is 137.Cm date . 138Valid 139.Ar FMT 140values are 141.Cm date , 142.Cm hours , 143.Cm minutes , 144and 145.Cm seconds . 146The date and time is formatted to the specified precision. 147When 148.Ar FMT 149is 150.Cm hours 151(or the more precise 152.Cm minutes 153or 154.Cm seconds ) , 155the 156.St -iso8601 157format includes the timezone. 158.It Fl j 159Do not try to set the date. 160This allows you to use the 161.Fl f 162flag in addition to the 163.Cm + 164option to convert one date format to another. 165Note that any date or time components unspecified by the 166.Fl f 167format string take their values from the current time. 168.It Fl n 169Obsolete flag, accepted and ignored for compatibility. 170.It Fl R 171Use RFC 2822 date and time output format. 172This is equivalent to using 173.Dq Li %a, %d %b %Y \&%T %z 174as 175.Ar output_fmt 176while 177.Ev LC_TIME 178is set to the 179.Dq C 180locale . 181.It Fl r Ar seconds 182Print the date and time represented by 183.Ar seconds , 184where 185.Ar seconds 186is the number of seconds since the Epoch 187(00:00:00 UTC, January 1, 1970; 188see 189.Xr time 3 ) , 190and can be specified in decimal, octal, or hex. 191.It Fl r Ar filename 192Print the date and time of the last modification of 193.Ar filename . 194.It Fl u 195Display or set the date in 196.Tn UTC 197(Coordinated Universal) time. 198By default 199.Nm 200displays the time in the time zone described by 201.Pa /etc/localtime 202or the 203.Ev TZ 204environment variable. 205.It Xo 206.Fl v 207.Sm off 208.Op Cm + | - 209.Ar val Op Cm y | m | w | d | H | M | S 210.Sm on 211.Xc 212Adjust (i.e., take the current date and display the result of the 213adjustment; not actually set the date) the second, minute, hour, month 214day, week day, month or year according to 215.Ar val . 216If 217.Ar val 218is preceded with a plus or minus sign, 219the date is adjusted forwards or backwards according to the remaining string, 220otherwise the relevant part of the date is set. 221The date can be adjusted as many times as required using these flags. 222Flags are processed in the order given. 223.Pp 224When setting values 225(rather than adjusting them), 226seconds are in the range 0-59, minutes are in the range 0-59, hours are 227in the range 0-23, month days are in the range 1-31, week days are in the 228range 0-6 (Sun-Sat), 229months are in the range 1-12 (Jan-Dec) 230and years are in the range 80-38 or 1980-2038. 231.Pp 232If 233.Ar val 234is numeric, one of either 235.Cm y , 236.Cm m , 237.Cm w , 238.Cm d , 239.Cm H , 240.Cm M 241or 242.Cm S 243must be used to specify which part of the date is to be adjusted. 244.Pp 245The week day or month may be specified using a name rather than a 246number. 247If a name is used with the plus 248(or minus) 249sign, the date will be put forwards 250(or backwards) 251to the next 252(previous) 253date that matches the given week day or month. 254This will not adjust the date, 255if the given week day or month is the same as the current one. 256.Pp 257When a date is adjusted to a specific value or in units greater than hours, 258daylight savings time considerations are ignored. 259Adjustments in units of hours or less honor daylight saving time. 260So, assuming the current date is March 26, 0:30 and that the DST adjustment 261means that the clock goes forward at 01:00 to 02:00, using 262.Fl v No +1H 263will adjust the date to March 26, 2:30. 264Likewise, if the date is October 29, 0:30 and the DST adjustment means that 265the clock goes back at 02:00 to 01:00, using 266.Fl v No +3H 267will be necessary to reach October 29, 2:30. 268.Pp 269When the date is adjusted to a specific value that does not actually exist 270(for example March 26, 1:30 BST 2000 in the Europe/London timezone), 271the date will be silently adjusted forwards in units of one hour until it 272reaches a valid time. 273When the date is adjusted to a specific value that occurs twice 274(for example October 29, 1:30 2000), 275the resulting timezone will be set so that the date matches the earlier of 276the two times. 277.Pp 278It is not possible to adjust a date to an invalid absolute day, so using 279the switches 280.Fl v No 31d Fl v No 12m 281will simply fail five months of the year. 282It is therefore usual to set the month before setting the day; using 283.Fl v No 12m Fl v No 31d 284always works. 285.Pp 286Adjusting the date by months is inherently ambiguous because 287a month is a unit of variable length depending on the current date. 288This kind of date adjustment is applied in the most intuitive way. 289First of all, 290.Nm 291tries to preserve the day of the month. 292If it is impossible because the target month is shorter than the present one, 293the last day of the target month will be the result. 294For example, using 295.Fl v No +1m 296on May 31 will adjust the date to June 30, while using the same option 297on January 30 will result in the date adjusted to the last day of February. 298This approach is also believed to make the most sense for shell scripting. 299Nevertheless, be aware that going forth and back by the same number of 300months may take you to a different date. 301.Pp 302Refer to the examples below for further details. 303.El 304.Pp 305An operand with a leading plus 306.Pq Sq + 307sign signals a user-defined format string 308which specifies the format in which to display the date and time. 309The format string may contain any of the conversion specifications 310described in the 311.Xr strftime 3 312manual page, as well as any arbitrary text. 313A newline 314.Pq Ql \en 315character is always output after the characters specified by 316the format string. 317The format string for the default display is 318.Dq +%+ . 319.Pp 320If an operand does not have a leading plus sign, it is interpreted as 321a value for setting the system's notion of the current date and time. 322The canonical representation for setting the date and time is: 323.Pp 324.Bl -tag -width Ds -compact -offset indent 325.It Ar cc 326Century 327(either 19 or 20) 328prepended to the abbreviated year. 329.It Ar yy 330Year in abbreviated form 331(e.g., 89 for 1989, 06 for 2006). 332.It Ar mm 333Numeric month, a number from 1 to 12. 334.It Ar dd 335Day, a number from 1 to 31. 336.It Ar HH 337Hour, a number from 0 to 23. 338.It Ar MM 339Minutes, a number from 0 to 59. 340.It Ar SS 341Seconds, a number from 0 to 60 342(59 plus a potential leap second). 343.El 344.Pp 345Everything but the minutes is optional. 346.Pp 347.Nm 348understands the time zone definitions in the 349.Sy tzdata 350package located in 351.Pa /usr/share/zoneinfo . 352Time changes for Daylight Saving Time, standard time, leap seconds 353and leap years are handled automatically. 354.Pp 355There are two ways to specify the time zone: 356.Pp 357If the file or symlink 358.Pa /etc/localtime 359exists, it is interpreted as a time zone definition file, usually in 360the directory hierarchy 361.Pa /usr/share/zoneinfo , 362which contains the time zone definitions from the 363.Sy tzdata 364package. 365.Pp 366If the environment variable 367.Ev TZ 368is set, its value is interpreted as the name of a time zone definition 369file, either an absolute path or a relative path to a time zone 370definition in 371.Pa /usr/share/zoneinfo . 372The 373.Ev TZ 374variable overrides 375.Pa /etc/localtime . 376.Pp 377If the time zone definition file is invalid, 378.Nm 379silently reverts to UTC. 380.Pp 381Previous versions of 382.Nm 383included the 384.Fl d 385(set daylight saving time flag) and 386.Fl t 387(set negative time zone offset) options, but these details are now 388handled automatically by 389.Sy tzdata . 390Modern offsets are positive for time zones ahead of UTC and negative 391for time zones behind UTC, but like the obsolete 392.Fl t 393option, the 394.Sy tzdata 395files in the subdirectory 396.Pa /usr/share/zoneinfo/Etc 397still use an older convention where times ahead of UTC are considered 398negative. 399.Sh ENVIRONMENT 400The following environment variable affects the execution of 401.Nm : 402.Bl -tag -width Ds 403.It Ev TZ 404The timezone to use when displaying dates. 405The normal format is a pathname relative to 406.Pa /usr/share/zoneinfo . 407For example, the command 408.Dq TZ=America/Los_Angeles date 409displays the current time in California. 410The variable can also specify an absolute path. 411See 412.Xr environ 7 413for more information. 414.El 415.Sh FILES 416.Bl -tag -width /var/log/messages -compact 417.It Pa /etc/localtime 418Time zone information file for default system time zone. 419May be omitted, in which case the default time zone is UTC. 420.It Pa /usr/share/zoneinfo 421Directory containing time zone information files. 422.It Pa /var/log/messages 423Record of the user setting the time. 424.It Pa /var/log/utx.log 425Record of date resets and time changes. 426.El 427.Sh EXIT STATUS 428The 429.Nm 430utility exits 0 on success, 1 if unable to set the date, and 2 431if able to set the local date, but unable to set it globally. 432.Sh EXAMPLES 433The command: 434.Pp 435.Dl "date ""+DATE: %Y-%m-%d%nTIME: %H:%M:%S""" 436.Pp 437will display: 438.Bd -literal -offset indent 439DATE: 1987-11-21 440TIME: 13:36:16 441.Ed 442.Pp 443In the Europe/London timezone, the command: 444.Pp 445.Dl "date -v1m -v+1y" 446.Pp 447will display: 448.Pp 449.Dl "Sun Jan 4 04:15:24 GMT 1998" 450.Pp 451where it is currently 452.Li "Mon Aug 4 04:15:24 BST 1997" . 453.Pp 454The command: 455.Pp 456.Dl "date -v1d -v3m -v0y -v-1d" 457.Pp 458will display the last day of February in the year 2000: 459.Pp 460.Dl "Tue Feb 29 03:18:00 GMT 2000" 461.Pp 462So will the command: 463.Pp 464.Dl "date -v3m -v30d -v0y -v-1m" 465.Pp 466because there is no such date as the 30th of February. 467.Pp 468The command: 469.Pp 470.Dl "date -v1d -v+1m -v-1d -v-fri" 471.Pp 472will display the last Friday of the month: 473.Pp 474.Dl "Fri Aug 29 04:31:11 BST 1997" 475.Pp 476where it is currently 477.Li "Mon Aug 4 04:31:11 BST 1997" . 478.Pp 479The command: 480.Pp 481.Dl "date 8506131627" 482.Pp 483sets the date to 484.Dq Li "June 13, 1985, 4:27 PM" . 485.Pp 486.Dl "date ""+%Y%m%d%H%M.%S""" 487.Pp 488may be used on one machine to print out the date 489suitable for setting on another. 490.Qq ( Li "+%m%d%H%M%Y.%S" 491for use on 492.Tn Linux . ) 493.Pp 494The command: 495.Pp 496.Dl "date 1432" 497.Pp 498sets the time to 499.Li "2:32 PM" , 500without modifying the date. 501.Pp 502The command 503.Pp 504.Dl "TZ=America/Los_Angeles date -Iseconds -r 1533415339" 505.Pp 506will display 507.Pp 508.Dl "2018-08-04T13:42:19-07:00" 509.Pp 510Finally the command: 511.Pp 512.Dl "date -j -f ""%a %b %d %T %Z %Y"" ""`LC_ALL=C date`"" ""+%s""" 513.Pp 514can be used to parse the output from 515.Nm 516and express it in Epoch time. 517.Sh DIAGNOSTICS 518It is invalid to combine the 519.Fl I 520flag with either 521.Fl R 522or an output format 523.Dq ( + Ns ... ) 524operand. 525If this occurs, 526.Nm 527prints: 528.Ql multiple output formats specified 529and exits with status 1. 530.Sh SEE ALSO 531.Xr locale 1 , 532.Xr gettimeofday 2 , 533.Xr getutxent 3 , 534.Xr strftime 3 , 535.Xr strptime 3 , 536.Xr tzset 3 , 537.Xr adjkerntz 8 , 538.Xr ntpd 8 , 539.Xr tzsetup 8 540.Rs 541.%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD" 542.%A R. Gusella 543.%A S. Zatti 544.Re 545.Rs 546.%U https://iana.org/time-zones 547.%T Time Zone Database 548.Re 549.Sh STANDARDS 550The 551.Nm 552utility is expected to be compatible with 553.St -p1003.2 . 554With the exception of the 555.Fl u 556option, all options are extensions to the standard. 557.Pp 558The format selected by the 559.Fl I 560flag is compatible with 561.St -iso8601 . 562.Sh HISTORY 563A 564.Nm 565command appeared in 566.At v1 . 567.Pp 568A number of options were added and then removed again, including the 569.Fl d 570(set DST flag) and 571.Fl t 572(set negative time zone offset). 573Time zones are now handled by the 574.Sy tzdata 575package. 576.Pp 577The 578.Fl I 579flag was added in 580.Fx 12.0 . 581