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

NAME
     date — display or set date and time

SYNOPSIS
     date [-ju] [-r seconds] [-v [+|-]val[ymwdHMS]] ... [+output_fmt]
     date [-jnu] [[[[[cc]yy]mm]dd]HH]MM[.ss]
     date [-jnu] -f input_fmt new_date [+output_fmt]
     date [-d dst] [-t minutes_west]

DESCRIPTION
     When invoked without arguments, the date utility displays the current
     date and time.  Otherwise, 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 hard‐
     ware clock are updated.

     Only the superuser may set the date, and if the system securelevel (see
     securelevel(7)) 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 input_fmt as the format string to parse the new_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 sup‐
	     presses 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 seconds since the Epoch (00:00:00 UTC, January 1,
	     1970; see time(3)), and can be specified 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
	     relevant 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 nec‐
	     essary to reach October 29, 2:30.

	     When the date is adjusted to a specific value that does not actu‐
	     ally exist (for example March 26, 1:30 BST 2000 in the
	     Europe/London timezone), the date will be silently adjusted for‐
	     wards 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.

	     It is not possible to adjust a date to an invalid absolute day,
	     so using the switches -v 31d -v 12m will simply fail five months
	     of the year.  It is therefore usual to set the month before set‐
	     ting the day; using -v 12m -v 31d always works.

	     Adjusting the date by months is inherently ambiguous because a
	     month is a unit of variable length depending on the current date.
	     This kind of date adjustment is applied in the most intuitive
	     way.  First of all, date tries to preserve the day of the month.
	     If it is impossible because the target month is shorter than the
	     present one, the last day of the target month will be the result.
	     For example, using -v +1m on May 31 will adjust the date to June
	     30, while using the same option on January 30 will result in the
	     date adjusted to the last day of February.	 This approach is also
	     believed to make the most sense for shell scripting.  Neverthe‐
	     less, be aware that going forth and back by the same number of
	     months may take you to a different date.

	     Refer to the examples below for further details.

     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 strftime(3) manual page, as well as any arbitrary text.
     A newline (‘\n’) character is always output after the characters speci‐
     fied 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 handled automatically.

ENVIRONMENT
     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.

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

EXIT STATUS
     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.

EXAMPLES
     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

     So will the command:

	   date -v3m -v30d -v0y -v-1m

     because there is no such date as the 30th of February.

     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”.

	   date "+%Y%m%d%H%M.%S"

     may be used on one machine to print out the date suitable for setting on
     another.  ("+%m%d%H%M%Y.%S" for use on Linux.)

     The command:

	   date 1432

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

     Finally the command:

	   date -j -f "%a %b %d %T %Z %Y" "`date`" "+%s"

     can be used to parse the output from date and express it in Epoch time.

DIAGNOSTICS
     Occasionally, when timed(8) synchronizes the time on many hosts, the set‐
     ting 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.

SEE ALSO
     locale(1), gettimeofday(2), strftime(3), strptime(3), utmp(5), timed(8)

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

STANDARDS
     The date utility is expected to be compatible with IEEE Std 1003.2
     (“POSIX.2”).  The -d, -f, -j, -n, -r, -t, and -v options are all exten‐
     sions to the standard.

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

BSD				 June 3, 2010				   BSD
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