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 May 19, 2023 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 z Ar output_zone 46.Op Fl I Ns Op Ar FMT 47.Op Fl r Ar filename 48.Op Fl r Ar seconds 49.Oo 50.Sm off 51.Fl v 52.Op Cm + | - 53.Ar val Op Cm y | m | w | d | H | M | S 54.Sm on 55.Oc 56.Op Cm + Ns Ar output_fmt 57.\" Set time with the default input format. 58.Nm 59.Op Fl jnRu 60.Op Fl z Ar output_zone 61.Op Fl I Ns Op Ar FMT 62.Oo 63.Sm off 64.Fl v 65.Op Cm + | - 66.Ar val Op Cm y | m | w | d | H | M | S 67.Sm on 68.Oc 69.Sm off 70.Oo Oo Oo Oo Oo 71.Ar cc Oc 72.Ar yy Oc 73.Ar mm Oc 74.Ar dd Oc 75.Ar HH 76.Oc Ar MM Op Cm \&. Ar SS 77.Sm on 78.Op Cm + Ns Ar output_fmt 79.\" Set time with the user-provided input format. 80.Nm 81.Op Fl jnRu 82.Op Fl z Ar output_zone 83.Op Fl I Ns Op Ar FMT 84.Oo 85.Sm off 86.Fl v 87.Op Cm + | - 88.Ar val Op Cm y | m | w | d | H | M | S 89.Sm on 90.Oc 91.Fl f Ar input_fmt 92.Ar new_date 93.Op Cm + Ns Ar output_fmt 94.Sh DESCRIPTION 95When invoked without arguments, the 96.Nm 97utility displays the current date and time. 98Otherwise, depending on the options specified, 99.Nm 100will set the date and time or print it in a user-defined way. 101.Pp 102The 103.Nm 104utility displays the date and time read from the kernel clock. 105When used to set the date and time, 106both the kernel clock and the hardware clock are updated. 107.Pp 108Only the superuser may set the date, 109and if the system securelevel (see 110.Xr securelevel 7 ) 111is greater than 1, 112the time may not be changed by more than 1 second. 113.Pp 114The options are as follows: 115.Bl -tag -width Ds 116.It Fl f Ar input_fmt 117Use 118.Ar input_fmt 119as the format string to parse the 120.Ar new_date 121provided rather than using the default 122.Sm off 123.Oo Oo Oo Oo Oo 124.Ar cc Oc 125.Ar yy Oc 126.Ar mm Oc 127.Ar dd Oc 128.Ar HH 129.Oc Ar MM Op Cm \&. Ar SS 130.Sm on 131format. 132Parsing is done using 133.Xr strptime 3 . 134.It Fl I Ns Op Ar FMT 135Use 136.St -iso8601 137output format. 138.Ar FMT 139may be omitted, in which case the default is 140.Cm date . 141Valid 142.Ar FMT 143values are 144.Cm date , 145.Cm hours , 146.Cm minutes , 147and 148.Cm seconds . 149The date and time is formatted to the specified precision. 150When 151.Ar FMT 152is 153.Cm hours 154(or the more precise 155.Cm minutes 156or 157.Cm seconds ) , 158the 159.St -iso8601 160format includes the timezone. 161.It Fl j 162Do not try to set the date. 163This allows you to use the 164.Fl f 165flag in addition to the 166.Cm + 167option to convert one date format to another. 168Note that any date or time components unspecified by the 169.Fl f 170format string take their values from the current time. 171.It Fl n 172Obsolete flag, accepted and ignored for compatibility. 173.It Fl R 174Use RFC 2822 date and time output format. 175This is equivalent to using 176.Dq Li %a, %d %b %Y \&%T %z 177as 178.Ar output_fmt 179while 180.Ev LC_TIME 181is set to the 182.Dq C 183locale . 184.It Fl r Ar seconds 185Print the date and time represented by 186.Ar seconds , 187where 188.Ar seconds 189is the number of seconds since the Epoch 190(00:00:00 UTC, January 1, 1970; 191see 192.Xr time 3 ) , 193and can be specified in decimal, octal, or hex. 194.It Fl r Ar filename 195Print the date and time of the last modification of 196.Ar filename . 197.It Fl u 198Display or set the date in 199.Tn UTC 200(Coordinated Universal) time. 201By default 202.Nm 203displays the time in the time zone described by 204.Pa /etc/localtime 205or the 206.Ev TZ 207environment variable. 208.It Fl z Ar output_zone 209Just before printing the time, change to the specified timezone; 210see the description of 211.Ev TZ 212below. 213This can be used with 214.Fl j 215to easily convert time specifications from one zone to another. 216.It Xo 217.Fl v 218.Sm off 219.Op Cm + | - 220.Ar val Op Cm y | m | w | d | H | M | S 221.Sm on 222.Xc 223Adjust (i.e., take the current date and display the result of the 224adjustment; not actually set the date) the second, minute, hour, month 225day, week day, month or year according to 226.Ar val . 227If 228.Ar val 229is preceded with a plus or minus sign, 230the date is adjusted forwards or backwards according to the remaining string, 231otherwise the relevant part of the date is set. 232The date can be adjusted as many times as required using these flags. 233Flags are processed in the order given. 234.Pp 235When setting values 236(rather than adjusting them), 237seconds are in the range 0-59, minutes are in the range 0-59, hours are 238in the range 0-23, month days are in the range 1-31, week days are in the 239range 0-6 (Sun-Sat), 240months are in the range 1-12 (Jan-Dec) 241and years are in a limited range depending on the platform. 242.Pp 243On i386, years are in the range 69-38 representing 1969-2038. 244On every other platform, years 0-68 are accepted and represent 2000-2068, and 24569-99 are accepted and represent 1969-1999. 246In both cases, years between 100 and 1900 (both included) are accepted and 247interpreted as relative to 1900 of the Gregorian calendar with a limit of 138 on 248i386 and a much higher limit on every other platform. 249Years starting at 1901 are also accepted, and are interpreted as absolute years. 250.Pp 251If 252.Ar val 253is numeric, one of either 254.Cm y , 255.Cm m , 256.Cm w , 257.Cm d , 258.Cm H , 259.Cm M 260or 261.Cm S 262must be used to specify which part of the date is to be adjusted. 263.Pp 264The week day or month may be specified using a name rather than a 265number. 266If a name is used with the plus 267(or minus) 268sign, the date will be put forwards 269(or backwards) 270to the next 271(previous) 272date that matches the given week day or month. 273This will not adjust the date, 274if the given week day or month is the same as the current one. 275.Pp 276When a date is adjusted to a specific value or in units greater than hours, 277daylight savings time considerations are ignored. 278Adjustments in units of hours or less honor daylight saving time. 279So, assuming the current date is March 26, 0:30 and that the DST adjustment 280means that the clock goes forward at 01:00 to 02:00, using 281.Fl v No +1H 282will adjust the date to March 26, 2:30. 283Likewise, if the date is October 29, 0:30 and the DST adjustment means that 284the clock goes back at 02:00 to 01:00, using 285.Fl v No +3H 286will be necessary to reach October 29, 2:30. 287.Pp 288When the date is adjusted to a specific value that does not actually exist 289(for example March 26, 1:30 BST 2000 in the Europe/London timezone), 290the date will be silently adjusted forwards in units of one hour until it 291reaches a valid time. 292When the date is adjusted to a specific value that occurs twice 293(for example October 29, 1:30 2000), 294the resulting timezone will be set so that the date matches the earlier of 295the two times. 296.Pp 297It is not possible to adjust a date to an invalid absolute day, so using 298the switches 299.Fl v No 31d Fl v No 12m 300will simply fail five months of the year. 301It is therefore usual to set the month before setting the day; using 302.Fl v No 12m Fl v No 31d 303always works. 304.Pp 305Adjusting the date by months is inherently ambiguous because 306a month is a unit of variable length depending on the current date. 307This kind of date adjustment is applied in the most intuitive way. 308First of all, 309.Nm 310tries to preserve the day of the month. 311If it is impossible because the target month is shorter than the present one, 312the last day of the target month will be the result. 313For example, using 314.Fl v No +1m 315on May 31 will adjust the date to June 30, while using the same option 316on January 30 will result in the date adjusted to the last day of February. 317This approach is also believed to make the most sense for shell scripting. 318Nevertheless, be aware that going forth and back by the same number of 319months may take you to a different date. 320.Pp 321Refer to the examples below for further details. 322.El 323.Pp 324An operand with a leading plus 325.Pq Sq + 326sign signals a user-defined format string 327which specifies the format in which to display the date and time. 328The format string may contain any of the conversion specifications 329described in the 330.Xr strftime 3 331manual page, as well as any arbitrary text. 332A newline 333.Pq Ql \en 334character is always output after the characters specified by 335the format string. 336The format string for the default display is 337.Dq +%+ . 338.Pp 339If an operand does not have a leading plus sign, it is interpreted as 340a value for setting the system's notion of the current date and time. 341The canonical representation for setting the date and time is: 342.Pp 343.Bl -tag -width Ds -compact -offset indent 344.It Ar cc 345Century 346(either 19 or 20) 347prepended to the abbreviated year. 348.It Ar yy 349Year in abbreviated form 350(e.g., 89 for 1989, 06 for 2006). 351.It Ar mm 352Numeric month, a number from 1 to 12. 353.It Ar dd 354Day, a number from 1 to 31. 355.It Ar HH 356Hour, a number from 0 to 23. 357.It Ar MM 358Minutes, a number from 0 to 59. 359.It Ar SS 360Seconds, a number from 0 to 60 361(59 plus a potential leap second). 362.El 363.Pp 364Everything but the minutes is optional. 365.Pp 366.Nm 367understands the time zone definitions from the IANA Time Zone Database, 368.Sy tzdata , 369located in 370.Pa /usr/share/zoneinfo . 371Time changes for Daylight Saving Time, standard time, leap seconds 372and leap years are handled automatically. 373.Pp 374There are two ways to specify the time zone: 375.Pp 376If the file or symlink 377.Pa /etc/localtime 378exists, it is interpreted as a time zone definition file, usually in 379the directory hierarchy 380.Pa /usr/share/zoneinfo , 381which contains the time zone definitions from 382.Sy tzdata . 383.Pp 384If the environment variable 385.Ev TZ 386is set, its value is interpreted as the name of a time zone definition 387file, either an absolute path or a relative path to a time zone 388definition in 389.Pa /usr/share/zoneinfo . 390The 391.Ev TZ 392variable overrides 393.Pa /etc/localtime . 394.Pp 395If the time zone definition file is invalid, 396.Nm 397silently reverts to UTC. 398.Pp 399Previous versions of 400.Nm 401included the 402.Fl d 403(set daylight saving time flag) and 404.Fl t 405(set negative time zone offset) options, but these details are now 406handled automatically by 407.Sy tzdata . 408Modern offsets are positive for time zones ahead of UTC and negative 409for time zones behind UTC, but like the obsolete 410.Fl t 411option, the 412.Sy tzdata 413files in the subdirectory 414.Pa /usr/share/zoneinfo/Etc 415still use an older convention where times ahead of UTC are considered 416negative. 417.Sh ENVIRONMENT 418The following environment variable affects the execution of 419.Nm : 420.Bl -tag -width Ds 421.It Ev TZ 422The timezone to use when displaying dates. 423The normal format is a pathname relative to 424.Pa /usr/share/zoneinfo . 425For example, the command 426.Dq TZ=America/Los_Angeles date 427displays the current time in California. 428The variable can also specify an absolute path. 429See 430.Xr environ 7 431for more information. 432.El 433.Sh FILES 434.Bl -tag -width /var/log/messages -compact 435.It Pa /etc/localtime 436Time zone information file for default system time zone. 437May be omitted, in which case the default time zone is UTC. 438.It Pa /usr/share/zoneinfo 439Directory containing time zone information files. 440.It Pa /var/log/messages 441Record of the user setting the time. 442.It Pa /var/log/utx.log 443Record of date resets and time changes. 444.El 445.Sh EXIT STATUS 446The 447.Nm 448utility exits 0 on success, 1 if unable to set the date, and 2 449if able to set the local date, but unable to set it globally. 450.Sh EXAMPLES 451The command: 452.Pp 453.Dl "date ""+DATE: %Y-%m-%d%nTIME: %H:%M:%S""" 454.Pp 455will display: 456.Bd -literal -offset indent 457DATE: 1987-11-21 458TIME: 13:36:16 459.Ed 460.Pp 461In the Europe/London timezone, the command: 462.Pp 463.Dl "date -v1m -v+1y" 464.Pp 465will display: 466.Pp 467.Dl "Sun Jan 4 04:15:24 GMT 1998" 468.Pp 469where it is currently 470.Li "Mon Aug 4 04:15:24 BST 1997" . 471.Pp 472The command: 473.Pp 474.Dl "date -v1d -v3m -v0y -v-1d" 475.Pp 476will display the last day of February in the year 2000: 477.Pp 478.Dl "Tue Feb 29 03:18:00 GMT 2000" 479.Pp 480So will the command: 481.Pp 482.Dl "date -v3m -v30d -v0y -v-1m" 483.Pp 484because there is no such date as the 30th of February. 485.Pp 486The command: 487.Pp 488.Dl "date -v1d -v+1m -v-1d -v-fri" 489.Pp 490will display the last Friday of the month: 491.Pp 492.Dl "Fri Aug 29 04:31:11 BST 1997" 493.Pp 494where it is currently 495.Li "Mon Aug 4 04:31:11 BST 1997" . 496.Pp 497The command: 498.Pp 499.Dl "date 8506131627" 500.Pp 501sets the date to 502.Dq Li "June 13, 1985, 4:27 PM" . 503.Pp 504.Dl "date ""+%Y%m%d%H%M.%S""" 505.Pp 506may be used on one machine to print out the date 507suitable for setting on another. 508.Qq ( Li "+%m%d%H%M%Y.%S" 509for use on 510.Tn Linux . ) 511.Pp 512The command: 513.Pp 514.Dl "date 1432" 515.Pp 516sets the time to 517.Li "2:32 PM" , 518without modifying the date. 519.Pp 520The command 521.Pp 522.Dl "TZ=America/Los_Angeles date -Iseconds -r 1533415339" 523.Pp 524will display 525.Pp 526.Dl "2018-08-04T13:42:19-07:00" 527.Pp 528The command: 529.Pp 530.Dl "env LC_ALL=C date -j -f ""%a %b %d %T %Z %Y"" ""`env LC_ALL=C date`"" ""+%s""" 531.Pp 532can be used to parse the output from 533.Nm 534and express it in Epoch time. 535.Pp 536Finally the command 537.Pp 538.Dl "TZ=America/Los_Angeles date -z Europe/Paris -j 0900" 539.Pp 540will print the time in the "Europe/Paris" timezone when it is 9:00 in The 541America/Los_Angeles timezone. 542.Sh DIAGNOSTICS 543It is invalid to combine the 544.Fl I 545flag with either 546.Fl R 547or an output format 548.Dq ( + Ns ... ) 549operand. 550If this occurs, 551.Nm 552prints: 553.Ql multiple output formats specified 554and exits with status 1. 555.Sh SEE ALSO 556.Xr locale 1 , 557.Xr gettimeofday 2 , 558.Xr getutxent 3 , 559.Xr strftime 3 , 560.Xr strptime 3 , 561.Xr tzset 3 , 562.Xr adjkerntz 8 , 563.Xr ntpd 8 , 564.Xr tzsetup 8 565.Rs 566.%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD" 567.%A R. Gusella 568.%A S. Zatti 569.Re 570.Rs 571.%U https://iana.org/time-zones 572.%T Time Zone Database 573.Re 574.Sh STANDARDS 575The 576.Nm 577utility is expected to be compatible with 578.St -p1003.2 . 579With the exception of the 580.Fl u 581option, all options are extensions to the standard. 582.Pp 583The format selected by the 584.Fl I 585flag is compatible with 586.St -iso8601 . 587.Sh HISTORY 588A 589.Nm 590command appeared in 591.At v1 . 592.Pp 593A number of options were added and then removed again, including the 594.Fl d 595(set DST flag) and 596.Fl t 597(set negative time zone offset). 598Time zones are now handled by code bundled with 599.Sy tzdata . 600.Pp 601The 602.Fl I 603flag was added in 604.Fx 12.0 . 605