GETTIMEOFDAY(2) UNIX Programmer's Manual GETTIMEOFDAY(2) NAME gettimeofday, settimeofday - get/set date and time SYNOPSIS #include gettimeofday(tp, tzp) struct timeval *tp; struct timezone *tzp; settimeofday(tp, tzp) struct timeval *tp; struct timezone *tzp; DESCRIPTION The system's notion of the current Greenwich time and the current time zone is obtained with the _g_e_t_t_i_m_e_o_f_d_a_y call, and set with the _s_e_t_t_i_m_e_o_f_d_a_y 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 _t_z_p is zero, the time zone information will not be returned or set. The structures pointed to by _t_p and _t_z_p are defined in <_s_y_s/_t_i_m_e._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 _t_i_m_e_z_o_n_e structure indicates the local time zone (meas- ured 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. RETURN 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 _e_r_r_n_o. ERRORS The following error codes may be set in _e_r_r_n_o: Printed 11/26/99 May 14, 1986 1 GETTIMEOFDAY(2) UNIX Programmer's Manual GETTIMEOFDAY(2) [EFAULT] An argument address referenced invalid memory. [EPERM] A user other than the super-user attempted to set the time. SEE ALSO date(1), adjtime(2), ctime(3), timed(8) Printed 11/26/99 May 14, 1986 2