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. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)date.1 8.2 (Berkeley) 11/17/93 36.\" $Id$ 37.\" 38.Dd November 17, 1993 39.Dt DATE 1 40.Os 41.Sh NAME 42.Nm date 43.Nd display or set date and time 44.Sh SYNOPSIS 45.Nm date 46.Op Fl d Ar dst 47.Op Fl r Ar seconds 48.Op Fl t Ar minutes_west 49.Op Fl nu 50.Op Cm + Ns Ar format 51.Op [yy[mm[dd[hh]]]]mm[\&.ss] 52.Sh DESCRIPTION 53.Nm Date 54displays the current date and time when invoked without arguments. 55Providing arguments will format the date and time in a user-defined 56way or set the date. 57Only the superuser may set the date. 58.Pp 59The options are as follows: 60.Bl -tag -width Ds 61.It Fl d 62Set the kernel's value for daylight savings time. 63If 64.Ar dst 65is non-zero, future calls 66to 67.Xr gettimeofday 2 68will return a non-zero 69.Ql tz_dsttime . 70.It Fl n 71The utility 72.Xr timed 8 73is used to synchronize the clocks on groups of machines. 74By default, if 75.Xr timed 76is running, 77.Nm date 78will set the time on all of the machines in the local group. 79The 80.Fl n 81option stops 82.Nm date 83from setting the time for other than the current machine. 84.It Fl r 85Print out the date and time in 86.Ar seconds 87from the Epoch. 88.It Fl t 89Set the kernel's value for minutes west of 90.Tn GMT . 91.Ar Minutes_west 92specifies the number of minutes returned in 93.Ql tz_minuteswest 94by future calls to 95.Xr gettimeofday 2 . 96.It Fl u 97Display or set the date in 98.Tn UCT 99(universal) time. 100.El 101.Pp 102An operand with a leading plus (``+'') sign signals a user-defined format 103string which specifies the format in which to display the date and time. 104The format string may contain any of the conversion specifications described 105in the 106.Xr strftime 3 107manual page, as well as any arbitrary text. 108The format string for the default display is: 109.Bd -literal -offset indent 110``%a %b %e %H:%M:%S %Z %Y%n''. 111.Ed 112.Pp 113If an operand does not have a leading plus sign, it is interpreted as 114a value for setting the system's notion of the current date and time. 115The canonical representation for setting the date and time is: 116.Pp 117.Bl -tag -width Ds -compact -offset indent 118.It Ar yy 119Year in abbreviated form (.e.g 89 for 1989). 120.It Ar mm 121Numeric month. 122A number from 1 to 12. 123.It Ar dd 124Day, a number from 1 to 31. 125.It Ar hh 126Hour, a number from 0 to 23. 127.It Ar mm 128Minutes, a number from 0 to 59. 129.It Ar .ss 130Seconds, a number from 0 to 61 (59 plus a a maximum of two leap seconds). 131.El 132.Pp 133Everything but the minutes is optional. 134.Pp 135Time changes for Daylight Saving and Standard time and leap seconds 136and years are handled automatically. 137.Sh EXAMPLES 138The command: 139.Bd -literal -offset indent 140date ``+DATE: %m/%d/%y%nTIME: %H:%M:%S%n'' 141.Ed 142.Pp 143will display: 144.Bd -literal -offset indent 145DATE: 11/21/87 146TIME: 13:36:16 147.Ed 148.Pp 149The command: 150.Bd -literal -offset indent 151date 8506131627 152.Ed 153.Pp 154sets the date to 155.Dq Li "June 13, 1985, 4:27 PM" . 156.Pp 157The command: 158.Bd -literal -offset indent 159date 1432 160.Ed 161.Pp 162sets the time to 163.Li "2:32 PM" , 164without modifying the date. 165.Sh ENVIRONMENTAL VARIABLES 166The following environment variables affect the execution of 167.Nm date : 168.Bl -tag -width Ds 169.It Ev TZ 170The timezone to use when displaying dates. 171See 172.Xr environ 7 173for more information. 174.El 175.Sh FILES 176.Bl -tag -width /var/log/messages -compact 177.It Pa /var/log/wtmp 178A record of date resets and time changes. 179.It Pa /var/log/messages 180A record of the user setting the time. 181.El 182.Sh SEE ALSO 183.Xr gettimeofday 2 , 184.Xr strftime 3 , 185.Xr utmp 5 , 186.Xr timed 8 187.Rs 188.%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD" 189.%A R. Gusella 190.%A S. Zatti 191.Re 192.Sh DIAGNOSTICS 193Exit status is 0 on success, 1 if unable to set the date, and 2 194if able to set the local date, but unable to set it globally. 195.Pp 196Occasionally, when 197.Xr timed 198synchronizes the time on many hosts, the setting of a new time value may 199require more than a few seconds. 200On these occasions, 201.Nm date 202prints: 203.Ql Network time being set . 204The message 205.Ql Communication error with timed 206occurs when the communication 207between 208.Nm date 209and 210.Xr timed 211fails. 212.Sh BUGS 213The system attempts to keep the date in a format closely compatible 214with 215.Tn VMS . 216.Tn VMS , 217however, uses local time (rather than 218.Tn GMT ) 219and does not understand daylight-savings time. 220Thus, if you use both 221.Tn UNIX 222and 223.Tn VMS , 224.Tn VMS 225will be running on 226.Tn GMT . 227.Sh STANDARDS 228The 229.Nm date 230command is expected to be compatible with 231.St -p1003.2 . 232