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gettimeofday(2)

utmp(5)

DATE(1)                              BSD                               DATE(1)



NAME
     date - print and set the date

SYNOPSIS
     date [ -n ] [ -u ] [ -f | -a ] [ yymmddhhmm[.ss] ]

DESCRIPTION
     If you don't specify an argument, date prints the current date and time.
     Providing an argument sets the desired date.  Only the super-user can set
     the date.

OPTIONS
     -u        Display or set the date in GMT (universal time).

      yymmddhhmm[.ss]
               If you're setting the date, yy represents the last two digits
               of the year; the first mm is the month number; dd is the day
               number; hh is the hour number (24-hour system); the second mm
               is the minute number; .ss is optional and represents the
               seconds.

               For example:

               date 8906131627

               sets the date to June 13 1989, 4:27 PM.  The year, month and
               day can be omitted; the default values will be the current
               ones.  The system operates in GMT.  The date command takes care
               of the conversion to and from local standard and daylight-
               saving time.

     -n        If timed is running to synchronize the clocks of machines in a
               local area network, date sets the time globally on all those
               machines, unless you specify the -n option.

     -f        Forces the time to be set backward.

               NOTE   At boot-time, the Domain/OS incorporates the current
                      date and time into the algorithm by which it computes
                      UIDs (unique identifiers).  After using date to set the
                      system time backwards, the user must not reboot the
                      machine until the previous system time has been passed.
                      Rebooting prior to this time will incur the risk that
                      the UID algorithm will incorporate a previously used
                      date and time into new UIDs.  As Domain/OS relies on the
                      uniqueness of UIDs, this can have devasting results.

     -a        If the target time has been set forward, the -a option will
               increment the sytem time at a faster rate until the target time
               (plus the elapsed real time) has been reached.  If the target
               time has been set backward, the -a option will retard
               advancement of the system time, gradually decreasing the
               difference between the two times, until the target time (plus
               the elapsed real time) is met.  This eliminates the possibility
               of duplicate UID generation.

DIAGNOSTICS
     Exit status is 0 on success; 1 on complete failure to set the date; 2 on
     successfully setting the local date but failing globally.

FILES
     /usr/adm/wtmp       To record time-setting.
     /usr/adm/messages   To record the name of the user setting the time.

WARNING
     Using date to set current date and time backwards can cause the creation
     of objects possessing previously assigned UIDs.

     At boot-time, the Domain/OS incorporates the current date and time into
     the algorithm by which it computes UIDs (unique identifiers).  After
     using date to set the system time backwards, the user must not reboot the
     machine until the previous system time has been passed.  Rebooting prior
     to this time will incur the risk that the UID algorithm will incorporate
     a previously used date and time into new UIDs.  As Domain/OS relies on
     the uniqueness of UIDs, this can have devastating results.

SEE ALSO
     gettimeofday(2), utmp(5)

Typewritten Software • bear@typewritten.org • Edmonds, WA 98026