Страницы справочника OS X

Эта страница руководства для  версии 10.9 Mac OS X

Читать страницы руководства

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] [[[mm]dd]HH]MM[[cc]yy][.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 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 input_fmt as the format string to parse the new_date provided rather than using the default
             [[[mm]dd]HH]MM[[cc]yy][.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 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 (previ-ous) (previous)
             ous) 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 does not actually exist (for example 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.

             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 Febru-ary. February.
             ary.  This approach is also believed to make the most sense for shell scripting.  Nevertheless,
             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 for-mat format
     mat in which to display the date and time.  The format string may contain any of the conversion speci-fications specifications
     fications described in the strftime(3) manual page, as well as any arbitrary 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 handled automat-ically. automatically.
     ically.

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/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 do the command:

           date -v30d -v3m -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 0613162785

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

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

     may be used on one machine to print out the date suitable for setting on another.

     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 setting of a new time value may
     require more than a few seconds.  On these occasions, date prints: `Network time being set'.  The mes-sage message
     sage `Communication error with timed' occurs when the communication between date and timed(8) fails.

LEGACY SYNOPSIS
     As above, except for the second line, which is:

     date [-jnu] [[[[[cc]yy]mm]dd]HH]MM[.ss]

LEGACY DIAGNOSTICS
     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

     For more information about legacy mode, see compat(5).

SEE ALSO
     gettimeofday(2), strftime(3), strptime(3), utmpx(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'').

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

BSD                             August 16, 2007                            BSD