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1 | .\" Copyright (c) 1980, 1990 The Regents of the University of California. |
2 | .\" 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 6.16 (Berkeley) 7/30/91 | |
36 | .\" | |
37 | .Dd July 30, 1991 | |
38 | .Dt DATE 1 | |
39 | .Os | |
40 | .Sh NAME | |
41 | .Nm date | |
42 | .Nd Display or set date and time | |
43 | .Sh SYNOPSIS | |
44 | .Nm date | |
45 | .Op Fl d Ar dst | |
46 | .Op Fl r Ar seconds | |
47 | .Op Fl t Ar minutes_west | |
48 | .Op Fl nu | |
49 | .Op Cm + Ns Ar format | |
50 | .Op [yy[mm[dd[hh]]]]mm[\&.ss] | |
51 | .Sh DESCRIPTION | |
52 | .Nm Date | |
53 | displays the current date and time when invoked without arguments. | |
54 | Providing arguments will format the date and time in a user-defined | |
55 | way or set the date. | |
56 | Only the superuser may set the date. | |
57 | .Pp | |
58 | The options are as follows: | |
59 | .Bl -tag -width Ds | |
60 | .It Fl d | |
61 | Set the kernel's values for daylight savings time. | |
62 | If | |
63 | .Ar dst | |
64 | is non-zero, future calls | |
65 | to | |
66 | .Xr gettimeofday 2 | |
67 | will return a non-zero | |
68 | .Ql tz_dsttime . | |
69 | .It Fl n | |
70 | The utility | |
71 | .Xr timed 8 | |
72 | is used to synchronize the clocks of groups of machines. | |
73 | By default, if | |
74 | .Xr timed | |
75 | is running, | |
76 | .Nm date | |
77 | will set the time on all of the machines in the local group. | |
78 | The | |
79 | .Fl n | |
80 | option stops | |
81 | .Nm date | |
82 | from setting the time for other than the current machine. | |
83 | .It Fl r | |
84 | Print out the date and time for | |
85 | .Ar seconds | |
86 | from the Epoch. | |
87 | .It Fl t | |
88 | Set the kernel's values for minutes west of | |
89 | .Tn GMT . | |
90 | .Ar Minutes_west | |
91 | specifies the number of minutes returned in | |
92 | .Ql tz_minuteswest | |
93 | by future calls to | |
94 | .Xr gettimeofday 2 . | |
95 | .It Fl u | |
96 | Display or set the date in | |
97 | .Tn UCT | |
98 | (universal) time. | |
99 | .El | |
100 | .Pp | |
101 | An operand with a leading plus (``+'') sign signals a user-defined format | |
102 | string which specifies the format in which to display the date and time. | |
103 | The format string may contain any of the conversion specifications described | |
104 | in the | |
105 | .Xr strftime 3 | |
106 | manual page, as well as any arbitrary text. | |
107 | The format string for the default display is: | |
108 | .Bd -literal -offset indent | |
109 | ``%a %b %e %H:%M:%S %Z n''. | |
110 | .Ed | |
111 | .Pp | |
112 | If an operand does not have a leading plus sign, it is interpreted as | |
113 | a value for setting the system's notion of the current date and time. | |
114 | The canonical representation for setting the date and time: | |
115 | .Pp | |
116 | .Bl -tag -width Ds -compact -offset indent | |
117 | .It Ar yy | |
118 | Year in abbreviated form (.e.g 89 for 1989). | |
119 | .It Ar mm | |
120 | Numeric month. | |
121 | A number from 1 to 12. | |
122 | .It Ar dd | |
123 | Day, a number from 1 to 31. | |
124 | .It Ar hh | |
125 | Hour, a number from 0 to 23. | |
126 | .It Ar mm | |
127 | Minutes, a number from 0 to 59. | |
128 | .It Ar .ss | |
129 | Seconds, a number from 0 to 59. | |
130 | .El | |
131 | .Pp | |
132 | Everything but the minutes are optional. | |
133 | .Pp | |
134 | Time changes for Daylight Saving and Standard time and leap seconds | |
135 | and years are handled automatically. | |
136 | .Sh EXAMPLES | |
137 | The command: | |
138 | .Bd -literal -offset indent | |
139 | date ``+DATE: %m/%d/%y%nTIME: %H:%M:%n'' | |
140 | .Ed | |
141 | .Pp | |
142 | will display: | |
143 | .Bd -literal -offset indent | |
144 | DATE: 11/21/87 | |
145 | TIME: 13:36:16 | |
146 | .Ed | |
147 | .Pp | |
148 | The command: | |
149 | .Bd -literal -offset indent | |
150 | date 8506131627 | |
151 | .Ed | |
152 | .Pp | |
153 | sets the date to | |
154 | .Dq Li "June 13 1985, 4:27 PM" . | |
155 | .Pp | |
156 | The command: | |
157 | .Bd -literal -offset indent | |
158 | date 1432 | |
159 | .Ed | |
160 | .Pp | |
161 | sets the time to | |
162 | .Li "2:32 PM" , | |
163 | without modifying the date. | |
164 | .Sh FILES | |
165 | .Bl -tag -width /var/log/messages -compact | |
166 | .It Pa /var/log/wtmp | |
167 | A record of date resets and time changes. | |
168 | .It Pa /var/log/messages | |
169 | A record of the user setting the time. | |
170 | .El | |
171 | .Sh SEE ALSO | |
172 | .Xr gettimeofday 2 , | |
173 | .Xr strftime 3 , | |
174 | .Xr utmp 5 , | |
175 | .Xr timed 8 | |
176 | .Rs | |
177 | .%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD" | |
178 | .%A R. Gusella | |
179 | .%A S. Zatti | |
180 | .Re | |
181 | .Sh DIAGNOSTICS | |
182 | Exit status is 0 on success, 1 if unable to set the date, and 2 | |
183 | if able to set the local date but failing to set it globally. | |
184 | .Pp | |
185 | Occasionally, when | |
186 | .Xr timed | |
187 | synchronizes the time on many hosts, the setting of a new time value may | |
188 | require more than a few seconds. | |
189 | On these occasions, | |
190 | .Nm date | |
191 | prints: | |
192 | .Ql Network time being set . | |
193 | The message | |
194 | .Ql Communication error with timed | |
195 | occurs when the communication | |
196 | between | |
197 | .Nm date | |
198 | and | |
199 | .Xr timed | |
200 | fails. | |
201 | .Sh BUGS | |
202 | The system attempts to keep the date in a format closely compatible | |
203 | with | |
204 | .Tn VMS . | |
205 | .Tn VMS , | |
206 | however, uses local time (rather than | |
207 | .Tn GMT ) | |
208 | and does not understand | |
209 | daylight-saving time. | |
210 | Thus, if you use both | |
211 | .Tn UNIX | |
212 | and | |
213 | .Tn VMS , | |
214 | .Tn VMS | |
215 | will be running on | |
216 | .Tn GMT . | |
217 | .Sh HISTORY | |
218 | The | |
219 | .Nm date | |
220 | command is expected to be compatible with | |
221 | .St p1003.2 . |