(BSD System Compatibility)

gettimeofday(3bsd)

gettimeofday, settimeofday -- (BSD) get or set the date and time

Synopsis

   /usr/ucb/cc [flag . . . ] file . . .
   
   #include <sys/time.h>
   

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

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

Description

The system's notion of the current Greenwich time is obtained with the gettimeofday call, and set with the settimeofday call. The current time is expressed in elapsed seconds and microseconds since 00:00 GMT, January 1, 1970 (zero hour). The resolution of the system clock is hardware dependent; the time may be updated continuously, or in ``ticks.''

tp points to a timeval structure, which includes the following members:

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

If tp is a NULL pointer, the current time information is not returned or set.

tzp is an obsolete pointer formerly used to get and set time zone information. tzp is now ignored. Time zone information is now handled using the TZ environment variable; see timezone(4).

Only the privileged user may set the time of day.

Return values

A -1 return value indicates an error occurred; in this case an error code is stored in the global variable errno.

The following error codes may be set in errno:

EINVAL: tp specifies an invalid time.
EPERM: A user other than the privileged user attempted to set the time.

References

adjtime(2), ctime(3C), date(1), gettimeofday(2), timezone(4)

Notices

Time is never correct enough to believe the microsecond values.

tzp is ignored.