GETTIMEOFDAY(2)
NAME
gettimeofday, settimeofday − get/set date and time
USAGE
#include <sys/time.h>
gettimeofday(tp, tzp)
struct timeval *tp;
struct timezone *tzp;
settimeofday(tp, tzp)
struct timeval *tp;
struct timezone *tzp;
DESCRIPTION
Gettimeofday returns the system’s idea of the current Greenwich time and the current time zone. Time returned is expressed in seconds and microseconds since midnight, January 1, 1970.
The structures pointed to by tp and tzp are defined in <sys/time.h> as:
struct timeval {
u_longtv_sec;/* seconds since Jan. 1, 1970 */
longtv_usec;/* and microseconds */
};
struct timezone {
inttz_minuteswest;/* of Greenwich */
inttz_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.
NOTES
Time is not correct to the microsecond values.
RETURN VALUE
A zero return value indicates that the call succeeded. A −1 return value indicates that an error occurred, and in this case, an error code is stored in the global variable errno.
ERRORS
The following error codes may be set in errno:
[EFAULT] An argument address referred to invalid memory.
[EPERM] A user other than the super-user attempted to set the time.