[apple/shell_cmds.git] / date / date.1

.\"	$NetBSD: date.1,v 1.22 1998/06/08 09:07:13 lukem Exp $
.\"
.\" Copyright (c) 1980, 1990, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" the Institute of Electrical and Electronics Engineers, Inc.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)date.1	8.3 (Berkeley) 4/28/95
.\"
.Dd September 22, 2004
.Dt DATE 1
.Os
.Sh NAME
.Nm date
.Nd display or set date and time
.Sh SYNOPSIS
.Nm
.Op Fl nu
.Op Fl r Ar seconds
.Op Cm + Ns Ar format
.Nm
.Op Fl u
.Ar mmddhhmm[[cc]yy]
.Sh DESCRIPTION
.Nm
displays the current date and time when invoked without arguments.
Providing arguments will format the date and time in a user-defined
way or set the date.  Only the superuser may set the date.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl n
The utility
.Xr timed 8
is used to synchronize the clocks on groups of machines.
By default, if
timed
is running,
.Nm
will set the time on all of the machines in the local group.
The
.Fl n
option stops
.Nm
from setting the time for other than the current machine.
.It Fl r
Print out the date and time that is
.Ar seconds
from the Epoch.
.It Fl u
Display or set the date in
.Tn UTC
(universal) time.
.El
.Pp
An operand with a leading plus (``+'') sign signals a user-defined format
string which specifies the format in which to display the date and time.
The format string may contain any of the conversion specifications described
in the 
.Xr strftime 3
manual page, as well as any arbitrary text.
A <newline> character is always output after the characters specified by
the format string.
The format string for the default display is:
.Bd -literal -offset indent
``%a %b %e %H:%M:%S %Z %Y''.
.Ed
.Pp
If an operand does not have a leading plus sign, it is interpreted as
a value for setting the system's notion of the current date and time.
The canonical representation for setting the date and time is:
.Pp
.Bl -tag -width Ds -compact -offset indent
.It Ar cc
The first two digits of the year (the century).
.It Ar yy
The second two digits of the year.  If
.Dq yy
is specified, but
.Dq cc
is not, a value for
.Dq yy
between 69 and 99 results in a
.Dq cc
value of 19.  Otherwise, a
.Dq cc
value of 20 is used.
.It Ar mm
The month of the year, from 1 to 12.
.It Ar dd
The day of the month, from 1 to 31.
.It Ar hh
The hour of the day, from 0 to 23.
.It Ar mm
The minute of the hour, from 0 to 59.
.It Ar ss
The second of the minute, from 0 to 61.
.El
.Pp
Everything but the minutes is optional.
.Pp
Time changes for Daylight Saving and Standard time and leap seconds
and years are handled automatically.
.Sh ENVIRONMENT VARIABLES
The following environment variables affect the execution of
.Nm
:
.Bl -tag -width TZ
.It Ev TZ
The timezone to use when displaying dates.
See
.Xr environ 7
for more information.
.El
.Sh FILES
.Bl -tag -width /var/log/messages -compact
.It Pa /var/log/wtmp
A record of date resets and time changes.
.It Pa /var/log/messages
A record of the user setting the time.
.El
.Sh EXAMPLES
The command:
.Bd -literal -offset indent
date "+DATE: %m/%d/%y%nTIME: %H:%M:%S"
.Ed
.Pp
will display:
.Bd -literal -offset indent
DATE: 11/21/87
TIME: 13:36:16
.Ed
.Pp
The command:
.Bd -literal -offset indent
date 061316271985
.Ed
.Pp
sets the date to
.Dq Li "June 13, 1985, 4:27 PM" .
.Pp
The command:
.Bd -literal -offset indent
date 1432
.Ed
.Pp
sets the time to
.Li "2:32 PM" ,
without modifying the date.
.Sh DIAGNOSTICS
The following exit values are returned:
 0    The date was written successfully (either locally or globally)
 >0   An error occurred.
.Pp
Occasionally, when
.Xr timed 8
synchronizes the time on many hosts, the setting of a new time value
may require more than a few seconds.
On these occasions,
.Nm
prints:
.Ql Network time being set .
The message
.Ql Communication error with timed
occurs when the communication
between
.Nm
and timed fails.
.Sh LEGACY SYNOPSIS
.Nm
.Op Fl nu
.Op Fl r Ar seconds
.Op Cm + Ns Ar format
.Pp
.Nm "    "
.Ar [[[[[cc]yy]mm]dd]hh]mm[\&.ss]
.Sh LEGACY DIAGNOSTICS
.Pp
When invoked in legacy mode the following exit values are returned:
 0    The date was written successfully
 1    Unable to set the date
 2    Able to set the local date, but unable to set it globally
.Sh SEE ALSO
.Xr gettimeofday 2 ,
.Xr strftime 3 ,
.Xr compat 5 ,
.Xr utmp 5 ,
.Xr timed 8
.Rs
.%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD"
.%A R. Gusella
.%A S. Zatti
.Re
.Sh STANDARDS
The
.Nm
utility supports the
.St -susv3 .
It is also expected to be compatible with
.St -p1003.2 .
Commit	Line	Data
44bd5ea7 A	1	.\" $NetBSD: date.1,v 1.22 1998/06/08 09:07:13 lukem Exp $
	2	.\"
	3	.\" Copyright (c) 1980, 1990, 1993
	4	.\" The Regents of the University of California. All rights reserved.
	5	.\"
	6	.\" This code is derived from software contributed to Berkeley by
	7	.\" the Institute of Electrical and Electronics Engineers, Inc.
	8	.\"
	9	.\" Redistribution and use in source and binary forms, with or without
	10	.\" modification, are permitted provided that the following conditions
	11	.\" are met:
	12	.\" 1. Redistributions of source code must retain the above copyright
	13	.\" notice, this list of conditions and the following disclaimer.
	14	.\" 2. Redistributions in binary form must reproduce the above copyright
	15	.\" notice, this list of conditions and the following disclaimer in the
	16	.\" documentation and/or other materials provided with the distribution.
	17	.\" 3. All advertising materials mentioning features or use of this software
	18	.\" must display the following acknowledgement:
	19	.\" This product includes software developed by the University of
	20	.\" California, Berkeley and its contributors.
	21	.\" 4. Neither the name of the University nor the names of its contributors
	22	.\" may be used to endorse or promote products derived from this software
	23	.\" without specific prior written permission.
	24	.\"
	25	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	26	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	27	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	28	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	29	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	30	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	31	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	32	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	33	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	34	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	35	.\" SUCH DAMAGE.
	36	.\"
	37	.\" @(#)date.1 8.3 (Berkeley) 4/28/95
	38	.\"
1c4c78a5	39	.Dd September 22, 2004
44bd5ea7 A	40	.Dt DATE 1
	41	.Os
	42	.Sh NAME
	43	.Nm date
	44	.Nd display or set date and time
	45	.Sh SYNOPSIS
	46	.Nm
	47	.Op Fl nu
	48	.Op Fl r Ar seconds
	49	.Op Cm + Ns Ar format
daf87b50	50	.Nm
1c4c78a5 A	51	.Op Fl u
1c4c78a5 A	52	.Ar mmddhhmm[[cc]yy]
44bd5ea7 A	53	.Sh DESCRIPTION
	54	.Nm
	55	displays the current date and time when invoked without arguments.
	56	Providing arguments will format the date and time in a user-defined
1c4c78a5	57	way or set the date. Only the superuser may set the date.
44bd5ea7 A	58	.Pp
	59	The options are as follows:
	60	.Bl -tag -width Ds
	61	.It Fl n
	62	The utility
	63	.Xr timed 8
	64	is used to synchronize the clocks on groups of machines.
	65	By default, if
	66	timed
	67	is running,
	68	.Nm
	69	will set the time on all of the machines in the local group.
	70	The
	71	.Fl n
	72	option stops
	73	.Nm
	74	from setting the time for other than the current machine.
	75	.It Fl r
	76	Print out the date and time that is
	77	.Ar seconds
	78	from the Epoch.
	79	.It Fl u
	80	Display or set the date in
	81	.Tn UTC
	82	(universal) time.
	83	.El
	84	.Pp
	85	An operand with a leading plus (``+'') sign signals a user-defined format
	86	string which specifies the format in which to display the date and time.
	87	The format string may contain any of the conversion specifications described
	88	in the
	89	.Xr strftime 3
	90	manual page, as well as any arbitrary text.
	91	A <newline> character is always output after the characters specified by
	92	the format string.
	93	The format string for the default display is:
	94	.Bd -literal -offset indent
	95	``%a %b %e %H:%M:%S %Z %Y''.
	96	.Ed
	97	.Pp
	98	If an operand does not have a leading plus sign, it is interpreted as
	99	a value for setting the system's notion of the current date and time.
	100	The canonical representation for setting the date and time is:
	101	.Pp
	102	.Bl -tag -width Ds -compact -offset indent
	103	.It Ar cc
	104	The first two digits of the year (the century).
	105	.It Ar yy
	106	The second two digits of the year. If
	107	.Dq yy
	108	is specified, but
	109	.Dq cc
	110	is not, a value for
	111	.Dq yy
	112	between 69 and 99 results in a
	113	.Dq cc
	114	value of 19. Otherwise, a
	115	.Dq cc
	116	value of 20 is used.
	117	.It Ar mm
	118	The month of the year, from 1 to 12.
	119	.It Ar dd
	120	The day of the month, from 1 to 31.
	121	.It Ar hh
122	The hour of the day, from 0 to 23.
123	.It Ar mm
124	The minute of the hour, from 0 to 59.
125	.It Ar ss
126	The second of the minute, from 0 to 61.
127	.El
128	.Pp
129	Everything but the minutes is optional.
130	.Pp
131	Time changes for Daylight Saving and Standard time and leap seconds
132	and years are handled automatically.
1c4c78a5 A	133	.Sh ENVIRONMENT VARIABLES
	134	The following environment variables affect the execution of
	135	.Nm
	136	:
	137	.Bl -tag -width TZ
	138	.It Ev TZ
	139	The timezone to use when displaying dates.
	140	See
	141	.Xr environ 7
	142	for more information.
	143	.El
	144	.Sh FILES
	145	.Bl -tag -width /var/log/messages -compact
	146	.It Pa /var/log/wtmp
	147	A record of date resets and time changes.
	148	.It Pa /var/log/messages
	149	A record of the user setting the time.
	150	.El
44bd5ea7 A	151	.Sh EXAMPLES
	152	The command:
	153	.Bd -literal -offset indent
9bafe280	154	date "+DATE: %m/%d/%y%nTIME: %H:%M:%S"
44bd5ea7 A	155	.Ed
	156	.Pp
	157	will display:
	158	.Bd -literal -offset indent
	159	DATE: 11/21/87
	160	TIME: 13:36:16
	161	.Ed
	162	.Pp
	163	The command:
	164	.Bd -literal -offset indent
1c4c78a5	165	date 061316271985
44bd5ea7 A	166	.Ed
	167	.Pp
	168	sets the date to
	169	.Dq Li "June 13, 1985, 4:27 PM" .
	170	.Pp
	171	The command:
	172	.Bd -literal -offset indent
	173	date 1432
	174	.Ed
	175	.Pp
	176	sets the time to
	177	.Li "2:32 PM" ,
	178	without modifying the date.
44bd5ea7	179	.Sh DIAGNOSTICS
1c4c78a5 A	180	The following exit values are returned:
	181	0 The date was written successfully (either locally or globally)
	182	>0 An error occurred.
44bd5ea7 A	183	.Pp
	184	Occasionally, when
	185	.Xr timed 8
1c4c78a5 A	186	synchronizes the time on many hosts, the setting of a new time value
1c4c78a5 A	187	may require more than a few seconds.
44bd5ea7 A	188	On these occasions,
	189	.Nm
	190	prints:
	191	.Ql Network time being set .
	192	The message
	193	.Ql Communication error with timed
	194	occurs when the communication
	195	between
	196	.Nm
1c4c78a5 A	197	and timed fails.
	198	.Sh LEGACY SYNOPSIS
	199	.Nm
	200	.Op Fl nu
	201	.Op Fl r Ar seconds
	202	.Op Cm + Ns Ar format
	203	.Pp
	204	.Nm " "
	205	.Ar [[[[[cc]yy]mm]dd]hh]mm[\&.ss]
	206	.Sh LEGACY DIAGNOSTICS
	207	.Pp
	208	When invoked in legacy mode the following exit values are returned:
	209	0 The date was written successfully
	210	1 Unable to set the date
	211	2 Able to set the local date, but unable to set it globally
	212	.Sh SEE ALSO
	213	.Xr gettimeofday 2 ,
	214	.Xr strftime 3 ,
	215	.Xr compat 5 ,
	216	.Xr utmp 5 ,
	217	.Xr timed 8
	218	.Rs
	219	.%T "TSP: The Time Synchronization Protocol for UNIX 4.3BSD"
	220	.%A R. Gusella
	221	.%A S. Zatti
	222	.Re
44bd5ea7 A	223	.Sh STANDARDS
	224	The
	225	.Nm
1c4c78a5 A	226	utility supports the
	227	.St -susv3 .
	228	It is also expected to be compatible with
44bd5ea7	229	.St -p1003.2 .