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GETTIMEOFDAY(2)		    BSD	System Calls Manual	       GETTIMEOFDAY(2)

NAME
     gettimeofday, settimeofday	-- get/set date	and time

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <sys/time.h>

     int
     gettimeofday(struct timeval * restrict tp,	void * restrict	tzp);

     int
     settimeofday(const	struct timeval * restrict tp,
	 const void * restrict tzp);

DESCRIPTION
     Note: time	zone information is no longer provided by this interface.  See
     localtime(3) for information on how to retrieve it.

     The system's notion of the	current	UTC time is obtained with the
     gettimeofday() call, and set with the settimeofday() call.	 The time is
     expressed in seconds and microseconds since midnight (0 hour), January 1,
     1970.  The	resolution of the system clock is hardware dependent, and the
     time may be updated continuously or in "ticks".

     If	tp is NULL, the	time will not be returned or set.  Despite being de-
     clared void *, the	objects	pointed	to by tzp shall	be of type struct
     timezone.

     The structures pointed to by tp and tzp are defined in <sys/time.h>.  The
     first one is described in timeval(3) and the latter legacy	structure is
     defined as:

	   struct timezone {
		   int	   tz_minuteswest; /* of Greenwich */
		   int	   tz_dsttime;	   /* type of dst correction to	apply */
	   };

     The timezone structure is provided	only for source	compatibility.	It is
     ignored by	settimeofday(),	and gettimeofday() will	always return zeroes.

     If	the calling user is not	the super-user,	then the settimeofday()	func-
     tion in the standard C library will try to	use the	clockctl(4) device if
     present, thus making possible for non privileged users to set the system
     time.  If clockctl(4) is not present or not accessible, then
     settimeofday() reverts to the settimeofday() system call, which is	re-
     stricted to the super user.

RETURN VALUES
     A return value 0 indicates	that the call succeeded.  A return value -1
     indicates an error	occurred, and in this case an error code is stored
     into the global variable errno.

ERRORS
     The following error codes may be set in errno:

     [EFAULT]		An argument address referenced invalid memory.

     [EPERM]		A user other than the super user attempted to set the
			time, or the specified time was	less than the current
			time, which was	not permitted at the current security
			level.

SEE ALSO
     date(1), adjtime(2), ctime(3), localtime(3), clockctl(4), timed(8)

HISTORY
     The gettimeofday()	function call appeared in 4.2BSD.  The tzp argument
     was deprecated in 4.4BSD (and many	other systems).

BSD				 May 18, 2010				   BSD

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | HISTORY

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