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 July 28, 2022 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 a limited range depending on the platform. 231.Pp 232On i386, years are in the range 69-38 representing 1969-2038. 233On every other platform, years 0-68 are accepted and represent 2000-2068, and 23469-99 are accepted and represent 1969-1999. 235In both cases, years between 100 and 1900 (both included) are accepted and 236interpreted as relative to 1900 of the Gregorian calendar with a limit of 138 on 237i386 and a much higher limit on every other platform. 238Years starting at 1901 are also accepted, and are interpreted as absolute years. 239.Pp 240If 241.Ar val 242is numeric, one of either 243.Cm y , 244.Cm m , 245.Cm w , 246.Cm d , 247.Cm H , 248.Cm M 249or 250.Cm S 251must be used to specify which part of the date is to be adjusted. 252.Pp 253The week day or month may be specified using a name rather than a 254number. 255If a name is used with the plus 256(or minus) 257sign, the date will be put forwards 258(or backwards) 259to the next 260(previous) 261date that matches the given week day or month. 262This will not adjust the date, 263if the given week day or month is the same as the current one. 264.Pp 265When a date is adjusted to a specific value or in units greater than hours, 266daylight savings time considerations are ignored. 267Adjustments in units of hours or less honor daylight saving time. 268So, assuming the current date is March 26, 0:30 and that the DST adjustment 269means that the clock goes forward at 01:00 to 02:00, using 270.Fl v No +1H 271will adjust the date to March 26, 2:30. 272Likewise, if the date is October 29, 0:30 and the DST adjustment means that 273the clock goes back at 02:00 to 01:00, using 274.Fl v No +3H 275will be necessary to reach October 29, 2:30. 276.Pp 277When the date is adjusted to a specific value that does not actually exist 278(for example March 26, 1:30 BST 2000 in the Europe/London timezone), 279the date will be silently adjusted forwards in units of one hour until it 280reaches a valid time. 281When the date is adjusted to a specific value that occurs twice 282(for example October 29, 1:30 2000), 283the resulting timezone will be set so that the date matches the earlier of 284the two times. 285.Pp 286It is not possible to adjust a date to an invalid absolute day, so using 287the switches 288.Fl v No 31d Fl v No 12m 289will simply fail five months of the year. 290It is therefore usual to set the month before setting the day; using 291.Fl v No 12m Fl v No 31d 292always works. 293.Pp 294Adjusting the date by months is inherently ambiguous because 295a month is a unit of variable length depending on the current date. 296This kind of date adjustment is applied in the most intuitive way. 297First of all, 298.Nm 299tries to preserve the day of the month. 300If it is impossible because the target month is shorter than the present one, 301the last day of the target month will be the result. 302For example, using 303.Fl v No +1m 304on May 31 will adjust the date to June 30, while using the same option 305on January 30 will result in the date adjusted to the last day of February. 306This approach is also believed to make the most sense for shell scripting. 307Nevertheless, be aware that going forth and back by the same number of 308months may take you to a different date. 309.Pp 310Refer to the examples below for further details. 311.El 312.Pp 313An operand with a leading plus 314.Pq Sq + 315sign signals a user-defined format string 316which specifies the format in which to display the date and time. 317The format string may contain any of the conversion specifications 318described in the 319.Xr strftime 3 320manual page, as well as any arbitrary text. 321A newline 322.Pq Ql \en 323character is always output after the characters specified by 324the format string. 325The format string for the default display is 326.Dq +%+ . 327.Pp 328If an operand does not have a leading plus sign, it is interpreted as 329a value for setting the system's notion of the current date and time. 330The canonical representation for setting the date and time is: 331.Pp 332.Bl -tag -width Ds -compact -offset indent 333.It Ar cc 334Century 335(either 19 or 20) 336prepended to the abbreviated year. 337.It Ar yy 338Year in abbreviated form 339(e.g., 89 for 1989, 06 for 2006). 340.It Ar mm 341Numeric month, a number from 1 to 12. 342.It Ar dd 343Day, a number from 1 to 31. 344.It Ar HH 345Hour, a number from 0 to 23. 346.It Ar MM 347Minutes, a number from 0 to 59. 348.It Ar SS 349Seconds, a number from 0 to 60 350(59 plus a potential leap second). 351.El 352.Pp 353Everything but the minutes is optional. 354.Pp 355.Nm 356understands the time zone definitions from the IANA Time Zone Database, 357.Sy tzdata , 358located in 359.Pa /usr/share/zoneinfo . 360Time changes for Daylight Saving Time, standard time, leap seconds 361and leap years are handled automatically. 362.Pp 363There are two ways to specify the time zone: 364.Pp 365If the file or symlink 366.Pa /etc/localtime 367exists, it is interpreted as a time zone definition file, usually in 368the directory hierarchy 369.Pa /usr/share/zoneinfo , 370which contains the time zone definitions from 371.Sy tzdata . 372.Pp 373If the environment variable 374.Ev TZ 375is set, its value is interpreted as the name of a time zone definition 376file, either an absolute path or a relative path to a time zone 377definition in 378.Pa /usr/share/zoneinfo . 379The 380.Ev TZ 381variable overrides 382.Pa /etc/localtime . 383.Pp 384If the time zone definition file is invalid, 385.Nm 386silently reverts to UTC. 387.Pp 388Previous versions of 389.Nm 390included the 391.Fl d 392(set daylight saving time flag) and 393.Fl t 394(set negative time zone offset) options, but these details are now 395handled automatically by 396.Sy tzdata . 397Modern offsets are positive for time zones ahead of UTC and negative 398for time zones behind UTC, but like the obsolete 399.Fl t 400option, the 401.Sy tzdata 402files in the subdirectory 403.Pa /usr/share/zoneinfo/Etc 404still use an older convention where times ahead of UTC are considered 405negative. 406.Sh ENVIRONMENT 407The following environment variable affects the execution of 408.Nm : 409.Bl -tag -width Ds 410.It Ev TZ 411The timezone to use when displaying dates. 412The normal format is a pathname relative to 413.Pa /usr/share/zoneinfo . 414For example, the command 415.Dq TZ=America/Los_Angeles date 416displays the current time in California. 417The variable can also specify an absolute path. 418See 419.Xr environ 7 420for more information. 421.El 422.Sh FILES 423.Bl -tag -width /var/log/messages -compact 424.It Pa /etc/localtime 425Time zone information file for default system time zone. 426May be omitted, in which case the default time zone is UTC. 427.It Pa /usr/share/zoneinfo 428Directory containing time zone information files. 429.It Pa /var/log/messages 430Record of the user setting the time. 431.It Pa /var/log/utx.log 432Record of date resets and time changes. 433.El 434.Sh EXIT STATUS 435The 436.Nm 437utility exits 0 on success, 1 if unable to set the date, and 2 438if able to set the local date, but unable to set it globally. 439.Sh EXAMPLES 440The command: 441.Pp 442.Dl "date ""+DATE: %Y-%m-%d%nTIME: %H:%M:%S""" 443.Pp 444will display: 445.Bd -literal -offset indent 446DATE: 1987-11-21 447TIME: 13:36:16 448.Ed 449.Pp 450In the Europe/London timezone, the command: 451.Pp 452.Dl "date -v1m -v+1y" 453.Pp 454will display: 455.Pp 456.Dl "Sun Jan 4 04:15:24 GMT 1998" 457.Pp 458where it is currently 459.Li "Mon Aug 4 04:15:24 BST 1997" . 460.Pp 461The command: 462.Pp 463.Dl "date -v1d -v3m -v0y -v-1d" 464.Pp 465will display the last day of February in the year 2000: 466.Pp 467.Dl "Tue Feb 29 03:18:00 GMT 2000" 468.Pp 469So will the command: 470.Pp 471.Dl "date -v3m -v30d -v0y -v-1m" 472.Pp 473because there is no such date as the 30th of February. 474.Pp 475The command: 476.Pp 477.Dl "date -v1d -v+1m -v-1d -v-fri" 478.Pp 479will display the last Friday of the month: 480.Pp 481.Dl "Fri Aug 29 04:31:11 BST 1997" 482.Pp 483where it is currently 484.Li "Mon Aug 4 04:31:11 BST 1997" . 485.Pp 486The command: 487.Pp 488.Dl "date 8506131627" 489.Pp 490sets the date to 491.Dq Li "June 13, 1985, 4:27 PM" . 492.Pp 493.Dl "date ""+%Y%m%d%H%M.%S""" 494.Pp 495may be used on one machine to print out the date 496suitable for setting on another. 497.Qq ( Li "+%m%d%H%M%Y.%S" 498for use on 499.Tn Linux . ) 500.Pp 501The command: 502.Pp 503.Dl "date 1432" 504.Pp 505sets the time to 506.Li "2:32 PM" , 507without modifying the date. 508.Pp 509The command 510.Pp 511.Dl "TZ=America/Los_Angeles date -Iseconds -r 1533415339" 512.Pp 513will display 514.Pp 515.Dl "2018-08-04T13:42:19-07:00" 516.Pp 517Finally the command: 518.Pp 519.Dl "date -j -f ""%a %b %d %T %Z %Y"" ""`LC_ALL=C date`"" ""+%s""" 520.Pp 521can be used to parse the output from 522.Nm 523and express it in Epoch time. 524.Sh DIAGNOSTICS 525It is invalid to combine the 526.Fl I 527flag with either 528.Fl R 529or an output format 530.Dq ( + Ns ... ) 531operand. 532If this occurs, 533.Nm 534prints: 535.Ql multiple output formats specified 536and exits with status 1. 537.Sh SEE ALSO 538.Xr locale 1 , 539.Xr gettimeofday 2 , 540.Xr getutxent 3 , 541.Xr strftime 3 , 542.Xr strptime 3 , 543.Xr tzset 3 , 544.Xr adjkerntz 8 , 545.Xr ntpd 8 , 546.Xr tzsetup 8 547.Rs 548.%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD" 549.%A R. Gusella 550.%A S. Zatti 551.Re 552.Rs 553.%U https://iana.org/time-zones 554.%T Time Zone Database 555.Re 556.Sh STANDARDS 557The 558.Nm 559utility is expected to be compatible with 560.St -p1003.2 . 561With the exception of the 562.Fl u 563option, all options are extensions to the standard. 564.Pp 565The format selected by the 566.Fl I 567flag is compatible with 568.St -iso8601 . 569.Sh HISTORY 570A 571.Nm 572command appeared in 573.At v1 . 574.Pp 575A number of options were added and then removed again, including the 576.Fl d 577(set DST flag) and 578.Fl t 579(set negative time zone offset). 580Time zones are now handled by code bundled with 581.Sy tzdata . 582.Pp 583The 584.Fl I 585flag was added in 586.Fx 12.0 . 587