OpenDarwin 7.2.1 - man page for date (opendarwin section 1)

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DATE(1) 			   BSD General Commands Manual				  DATE(1)

     date -- display or set date and time

     date [-jnu] [-d dst] [-r seconds] [-t minutes_west] [-v [+|-]val[ymwdHMS]] ... [-f fmt date
	  | [[[[[cc]yy]mm]dd]HH]MM[.ss]] [+format]

     When invoked without arguments, the date utility displays the current date and time.  Other-
     wise, depending on the options specified, date will set the date and time or print it in a
     user-defined way.

     The date utility displays the date and time read from the kernel clock.  When used to set
     the date and time, both the kernel clock and the hardware clock are updated.

     Only the superuser may set the date, and if the system securelevel (see securelevel(8)) is
     greater than 1, the time may not be changed by more than 1 second.

     The options are as follows:

     -d dst  Set the kernel's value for daylight saving time.  If dst is non-zero, future calls
	     to gettimeofday(2) will return a non-zero for tz_dsttime.

     -f      Use fmt as the format string to parse the date provided rather than using the
	     default [[[[[cc]yy]mm]dd]HH]MM[.ss] format.  Parsing is done using strptime(3).

     -j      Do not try to set the date.  This allows you to use the -f flag in addition to the +
	     option to convert one date format to another.

     -n      By default, if the timed(8) daemon is running, date sets the time on all of the
	     machines in the local group.  The -n option suppresses this behavior and causes the
	     time to be set only on the current machine.

     -r seconds
	     Print the date and time represented by seconds, where seconds is the number of sec-
	     onds since the Epoch (00:00:00 UTC, January 1, 1970; see time(3)), and can be speci-
	     fied in decimal, octal, or hex.

     -t minutes_west
	     Set the system's value for minutes west of GMT.  minutes_west specifies the number
	     of minutes returned in tz_minuteswest by future calls to gettimeofday(2).

     -u      Display or set the date in UTC (Coordinated Universal) time.

     -v      Adjust (i.e., take the current date and display the result of the adjustment; not
	     actually set the date) the second, minute, hour, month day, week day, month or year
	     according to val.	If val is preceded with a plus or minus sign, the date is
	     adjusted forwards or backwards according to the remaining string, otherwise the rel-
	     evant part of the date is set.  The date can be adjusted as many times as required
	     using these flags.  Flags are processed in the order given.

	     When setting values (rather than adjusting them), seconds are in the range 0-59,
	     minutes are in the range 0-59, hours are in the range 0-23, month days are in the
	     range 1-31, week days are in the range 0-6 (Sun-Sat), months are in the range 1-12
	     (Jan-Dec) and years are in the range 80-38 or 1980-2038.

	     If val is numeric, one of either y, m, w, d, H, M or S must be used to specify which
	     part of the date is to be adjusted.

	     The week day or month may be specified using a name rather than a number.	If a name
	     is used with the plus (or minus) sign, the date will be put forwards (or backwards)
	     to the next (previous) date that matches the given week day or month.  This will not
	     adjust the date, if the given week day or month is the same as the current one.

	     When a date is adjusted to a specific value or in units greater than hours, daylight
	     savings time considerations are ignored.  Adjustments in units of hours or less
	     honor daylight saving time.  So, assuming the current date is March 26, 0:30 and
	     that the DST adjustment means that the clock goes forward at 01:00 to 02:00, using
	     -v +1H will adjust the date to March 26, 2:30.  Likewise, if the date is October 29,
	     0:30 and the DST adjustment means that the clock goes back at 02:00 to 01:00, using
	     -v +3H will be necessary to reach October 29, 2:30.

	     When the date is adjusted to a specific value that doesn't actually exist (for exam-
	     ple March 26, 1:30 BST 2000 in the Europe/London timezone), the date will be
	     silently adjusted forwards in units of one hour until it reaches a valid time.  When
	     the date is adjusted to a specific value that occurs twice (for example October 29,
	     1:30 2000), the resulting timezone will be set so that the date matches the earlier
	     of the two times.

	     Refer to the examples below for further details.

     An operand with a leading plus ('+') sign signals a user-defined format string which speci-
     fies the format in which to display the date and time.  The format string may contain any of
     the conversion specifications described in the strftime(3) manual page, as well as any arbi-
     trary text.  A newline ('\n') character is always output after the characters specified by
     the format string.  The format string for the default display is ``+%+''.

     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:

	   cc	   Century (either 19 or 20) prepended to the abbreviated year.
	   yy	   Year in abbreviated form (e.g. 89 for 1989, 06 for 2006).
	   mm	   Numeric month, a number from 1 to 12.
	   dd	   Day, a number from 1 to 31.
	   HH	   Hour, a number from 0 to 23.
	   MM	   Minutes, a number from 0 to 59.
	   ss	   Seconds, a number from 0 to 61 (59 plus a maximum of two leap seconds).

     Everything but the minutes is optional.

     Time changes for Daylight Saving Time, standard time, leap seconds, and leap years are han-
     dled automatically.

     The command:

	   date "+DATE: %Y-%m-%d%nTIME: %H:%M:%S"

     will display:

	   DATE: 1987-11-21
	   TIME: 13:36:16

     In the Europe/London timezone, the command:

	   date -v1m -v+1y

     will display:

	   Sun Jan  4 04:15:24 GMT 1998

     where it is currently Mon Aug  4 04:15:24 BST 1997.

     The command:

	   date -v1d -v3m -v0y -v-1d

     will display the last day of February in the year 2000:

	   Tue Feb 29 03:18:00 GMT 2000

     The command:

	   date -v1d -v+1m -v-1d -v-fri

     will display the last Friday of the month:

	   Fri Aug 29 04:31:11 BST 1997

     where it is currently Mon Aug  4 04:31:11 BST 1997.

     The command:

	   date 8506131627

     sets the date to ``June 13, 1985, 4:27 PM''.

     The command:

	   date 1432

     sets the time to 2:32 PM, without modifying the date.

     The following environment variables affect the execution of date:

     TZ      The timezone to use when displaying dates.  The normal format is a pathname relative
	     to /usr/share/zoneinfo.  For example, the command ``TZ=America/Los_Angeles date''
	     displays the current time in California.  See environ(7) for more information.

     /var/log/wtmp	record of date resets and time changes
     /var/log/messages	record of the user setting the time

     gettimeofday(2), strftime(3), strptime(3), utmp(5), timed(8)

     R. Gusella and S. Zatti, TSP: The Time Synchronization Protocol for UNIX 4.3BSD.

     The date utility exits 0 on success, 1 if unable to set the date, and 2 if able to set the
     local date, but unable to set it globally.

     Occasionally, when 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, date prints: 'Network time
     being set'.  The message 'Communication error with timed' occurs when the communication
     between date and timed(8) fails.

     The date utility is expected to be compatible with IEEE Std 1003.2 (``POSIX.2'').

     A date command appeared in Version 1 AT&T UNIX.

BSD					November 17, 1993				      BSD
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