gettimeofday man page on 4.4BSD

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

     gettimeofday, settimeofday — get/set date and time

     #include <sys/time.h>

     gettimeofday(struct timeval *tp, struct timezone *tzp);

     settimeofday(struct timeval *tp, struct timezone *tzp);

     Note: timezone is no longer used; this information is kept outside the
     kernel.  The system's notion of the current Greenwich time and the cur‐
     rent time zone 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 or tzp is NULL, the associated time information will
     not be returned or set.

     The structures pointed to by tp and tzp are defined in ⟨sys/time.h⟩ as:

     struct timeval {
	     long    tv_sec;	     /* seconds since Jan. 1, 1970 */
	     long    tv_usec;	     /* and microseconds */

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

     The timezone structure indicates the local time zone (measured in minutes
     of time westward from Greenwich), and a flag that, if nonzero, indicates
     that Daylight Saving time applies locally during the appropriate part of
     the year.

     Only the super-user may set the time of day or time zone.	If the system
     is running in secure mode (see init(8) ), the time may only be advanced.
     This limitation is imposed to prevent a malicious super-user from setting
     arbitrary time stamps on files.  The system time can still be adjusted
     backwards using the adjtime(2) system call even when the system is

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

     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.

     date(1), adjtime(2), ctime(3), timed(8)

     The gettimeofday function call appeared in 4.2BSD.

4th Berkeley Distribution	 May 26, 1995	     4th Berkeley Distribution

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