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.\" $DragonFly: src/bin/date/date.1,v 1.4 2005/07/20 20:05:46 cpressey Exp $ 34.\" 35.Dd August 9, 2004 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 ju 44.Op Fl r Ar seconds 45.Oo 46.Fl v 47.Sm off 48.Op Cm + | - 49.Ar val Op Ar ymwdHMS 50.Sm on 51.Oc 52.Ar ... 53.Op Cm + Ns Ar output_fmt 54.Nm 55.Op Fl jnu 56.Sm off 57.Op Oo Oo Oo Oo Ar cc Oc Ar yy Oc Ar mm Oc Ar dd Oc Ar HH 58.Ar MM Op Ar .ss 59.Sm on 60.Nm 61.Op Fl jnu 62.Fl f Ar input_fmt new_date 63.Op Cm + Ns Ar output_fmt 64.Nm 65.Op Fl d Ar dst 66.Op Fl t Ar minutes_west 67.Sh DESCRIPTION 68When invoked without arguments, the 69.Nm 70utility displays the current date and time. 71Otherwise, depending on the options specified, 72.Nm 73will set the date and time or print it in a user-defined way. 74.Pp 75The 76.Nm 77utility displays the date and time read from the kernel clock. 78When used to set the date and time, 79both the kernel clock and the hardware clock are updated. 80.Pp 81Only the superuser may set the date, 82and if the system securelevel (see 83.Xr securelevel 8 ) 84is greater than 1, 85the time may not be changed by more than 1 second. 86.Pp 87The options are as follows: 88.Bl -tag -width Ds 89.It Fl d Ar dst 90Set the kernel's value for daylight saving time. 91If 92.Ar dst 93is non-zero, future calls 94to 95.Xr gettimeofday 2 96will return a non-zero for 97.Fa tz_dsttime . 98.It Fl f 99Use 100.Ar input_fmt 101as the format string to parse the 102.Ar new_date 103provided rather than using the default 104.Sm off 105.Oo Oo Oo Oo Oo 106.Ar cc Oc 107.Ar yy Oc 108.Ar mm Oc 109.Ar dd Oc 110.Ar HH 111.Oc Ar MM Op Ar .ss 112.Sm on 113format. 114Parsing is done using 115.Xr strptime 3 . 116.It Fl j 117Do not try to set the date. 118This allows you to use the 119.Fl f 120flag in addition to the 121.Cm + 122option to convert one date format to another. 123.It Fl n 124By default, if the 125.Xr timed 8 126daemon is running, 127.Nm 128sets the time on all of the machines in the local group. 129The 130.Fl n 131option suppresses this behavior and causes the time to be set only on the 132current machine. 133.It Fl r Ar seconds 134Print the date and time represented by 135.Ar seconds , 136where 137.Ar seconds 138is the number of seconds since the Epoch 139(00:00:00 UTC, January 1, 1970; 140see 141.Xr time 3 ) , 142and can be specified in decimal, octal, or hex. 143.It Fl t Ar minutes_west 144Set the system's value for minutes west of 145.Tn GMT . 146.Ar minutes_west 147specifies the number of minutes returned in 148.Fa tz_minuteswest 149by future calls to 150.Xr gettimeofday 2 . 151.It Fl u 152Display or set the date in 153.Tn UTC 154(Coordinated Universal) time. 155.It Fl v 156Adjust (i.e., take the current date and display the result of the 157adjustment; not actually set the date) the second, minute, hour, month 158day, week day, month or year according to 159.Ar val . 160If 161.Ar val 162is preceded with a plus or minus sign, 163the date is adjusted forwards or backwards according to the remaining string, 164otherwise the relevant part of the date is set. 165The date can be adjusted as many times as required using these flags. 166Flags are processed in the order given. 167.Pp 168When setting values 169(rather than adjusting them), 170seconds are in the range 0-59, minutes are in the range 0-59, hours are 171in the range 0-23, month days are in the range 1-31, week days are in the 172range 0-6 (Sun-Sat), 173months are in the range 1-12 (Jan-Dec) 174and years are in the range 80-38 or 1980-2038. 175.Pp 176If 177.Ar val 178is numeric, one of either 179.Ar y , 180.Ar m , 181.Ar w , 182.Ar d , 183.Ar H , 184.Ar M 185or 186.Ar S 187must be used to specify which part of the date is to be adjusted. 188.Pp 189The week day or month may be specified using a name rather than a 190number. 191If a name is used with the plus 192(or minus) 193sign, the date will be put forwards 194(or backwards) 195to the next 196(previous) 197date that matches the given week day or month. 198This will not adjust the date, 199if the given week day or month is the same as the current one. 200.Pp 201When a date is adjusted to a specific value or in units greater than hours, 202daylight savings time considerations are ignored. 203Adjustments in units of hours or less honor daylight saving time. 204So, assuming the current date is March 26, 0:30 and that the DST adjustment 205means that the clock goes forward at 01:00 to 02:00, using 206.Fl v No +1H 207will adjust the date to March 26, 2:30. 208Likewise, if the date is October 29, 0:30 and the DST adjustment means that 209the clock goes back at 02:00 to 01:00, using 210.Fl v No +3H 211will be necessary to reach October 29, 2:30. 212.Pp 213When the date is adjusted to a specific value that does not actually exist 214(for example March 26, 1:30 BST 2000 in the Europe/London timezone), 215the date will be silently adjusted forwards in units of one hour until it 216reaches a valid time. 217When the date is adjusted to a specific value that occurs twice 218(for example October 29, 1:30 2000), 219the resulting timezone will be set so that the date matches the earlier of 220the two times. 221.Pp 222Adjusting the date by months is inherently ambiguous because 223a month is a unit of variable length depending on the current date. 224This kind of date adjustment is applied in the most intuitive way. 225First of all, 226.Nm 227tries to preserve the day of the month. 228If it is impossible because the target month is shorter than the present one, 229the last day of the target month will be the result. 230For example, using 231.Fl v No +1m 232on May 31 will adjust the date to June 30, while using the same option 233on January 30 will result in the date adjusted to the last day of February. 234This approach is also believed to make the most sense for shell scripting. 235Nevertheless, be aware that going forth and back by the same number of 236months may take you to a different date. 237.Pp 238Refer to the examples below for further details. 239.El 240.Pp 241An operand with a leading plus 242.Pq Sq + 243sign signals a user-defined format string 244which specifies the format in which to display the date and time. 245The format string may contain any of the conversion specifications 246described in the 247.Xr strftime 3 248manual page, as well as any arbitrary text. 249A newline 250.Pq Ql \en 251character is always output after the characters specified by 252the format string. 253The format string for the default display is 254.Dq +%+ . 255.Pp 256If an operand does not have a leading plus sign, it is interpreted as 257a value for setting the system's notion of the current date and time. 258The canonical representation for setting the date and time is: 259.Pp 260.Bl -tag -width Ds -compact -offset indent 261.It Ar cc 262Century 263(either 19 or 20) 264prepended to the abbreviated year. 265.It Ar yy 266Year in abbreviated form 267(e.g., 89 for 1989, 06 for 2006). 268.It Ar mm 269Numeric month, a number from 1 to 12. 270.It Ar dd 271Day, a number from 1 to 31. 272.It Ar HH 273Hour, a number from 0 to 23. 274.It Ar MM 275Minutes, a number from 0 to 59. 276.It Ar ss 277Seconds, a number from 0 to 61 278(59 plus a maximum of two leap seconds). 279.El 280.Pp 281Everything but the minutes is optional. 282.Pp 283Time changes for Daylight Saving Time, standard time, leap seconds, 284and leap years are handled automatically. 285.Sh ENVIRONMENT 286The following environment variables affect the execution of 287.Nm : 288.Bl -tag -width Ds 289.It Ev TZ 290The timezone to use when displaying dates. 291The normal format is a pathname relative to 292.Pa /usr/share/zoneinfo . 293For example, the command 294.Dq TZ=America/Los_Angeles date 295displays the current time in California. 296See 297.Xr environ 7 298for more information. 299.El 300.Sh FILES 301.Bl -tag -width /var/log/messages -compact 302.It Pa /var/log/wtmp 303record of date resets and time changes 304.It Pa /var/log/messages 305record of the user setting the time 306.El 307.Sh EXIT STATUS 308The 309.Nm 310utility exits 0 on success, 1 if unable to set the date, and 2 311if able to set the local date, but unable to set it globally. 312.Sh EXAMPLES 313The command: 314.Pp 315.Dl "date ""+DATE: %Y-%m-%d%nTIME: %H:%M:%S""" 316.Pp 317will display: 318.Bd -literal -offset indent 319DATE: 1987-11-21 320TIME: 13:36:16 321.Ed 322.Pp 323In the Europe/London timezone, the command: 324.Pp 325.Dl "date -v1m -v+1y" 326.Pp 327will display: 328.Pp 329.Dl "Sun Jan 4 04:15:24 GMT 1998" 330.Pp 331where it is currently 332.Li "Mon Aug 4 04:15:24 BST 1997" . 333.Pp 334The command: 335.Pp 336.Dl "date -v1d -v3m -v0y -v-1d" 337.Pp 338will display the last day of February in the year 2000: 339.Pp 340.Dl "Tue Feb 29 03:18:00 GMT 2000" 341.Pp 342So will do the command: 343.Pp 344.Dl "date -v30d -v3m -v0y -v-1m" 345.Pp 346because there is no such date as the 30th of February. 347.Pp 348The command: 349.Pp 350.Dl "date -v1d -v+1m -v-1d -v-fri" 351.Pp 352will display the last Friday of the month: 353.Pp 354.Dl "Fri Aug 29 04:31:11 BST 1997" 355.Pp 356where it is currently 357.Li "Mon Aug 4 04:31:11 BST 1997" . 358.Pp 359The command: 360.Pp 361.Dl "date 8506131627" 362.Pp 363sets the date to 364.Dq Li "June 13, 1985, 4:27 PM" . 365.Pp 366.Dl "date ""+%Y%m%d%H%M.%S""" 367.Pp 368may be used on one machine to print out the date 369suitable for setting on another. 370.Qq ( Li "+%m%d%H%M%Y.%S" 371for use on 372.Tn Linux . ) 373.Pp 374The command: 375.Pp 376.Dl "date 1432" 377.Pp 378sets the time to 379.Li "2:32 PM" , 380without modifying the date. 381.Pp 382Finally the command: 383.Pp 384.Dl "date -j -f ""%a %b %d %T %Z %Y"" ""`date`"" ""+%s""" 385.Pp 386can be used to parse the output from 387.Nm 388and express it in Epoch time. 389.Sh DIAGNOSTICS 390Occasionally, when 391.Xr timed 8 392synchronizes the time on many hosts, the setting of a new time value may 393require more than a few seconds. 394On these occasions, 395.Nm 396prints: 397.Ql Network time being set . 398The message 399.Ql Communication error with timed 400occurs when the communication 401between 402.Nm 403and 404.Xr timed 8 405fails. 406.Sh SEE ALSO 407.Xr gettimeofday 2 , 408.Xr strftime 3 , 409.Xr strptime 3 , 410.Xr utmp 5 , 411.Xr timed 8 412.Rs 413.%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD" 414.%A R. Gusella 415.%A S. Zatti 416.Re 417.Sh STANDARDS 418The 419.Nm 420utility is expected to be compatible with 421.St -p1003.2 . 422.Sh HISTORY 423A 424.Nm 425command appeared in 426.At v1 . 427