gettimeofday(2)
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gettimeofday System Call
Get date and time.
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SYNTAX
#include <sys/time.h>
int gettimeofday (time_value, time_zone)
struct timeval * time_value;
struct timezone * time_zone;
PARAMETERS
time_value Address of a structure that will be set to the
current time.
time_zone NULL or address of a structure that will be set to
the current time zone.
DESCRIPTION
Gettimeofday returns the system's notion of the current Greenwich
time and the current time zone to the structures at the locations
specified by <time_value> and <time_zone>.
If <time_zone> is NULL, the current time zone is not returned.
The time value returned is Greenwich time expressed in seconds
and microseconds since midnight January 1, 1970.
The local time zone is expressed in minutes of time westward from
Greenwich (tz_minuteswest), and a value (tz_dsttime) that
indicates the type of daylight savings time that applies locally
during the appropriate part of the year. The daylight savings
time correction flag (tz_dsttime) further indicates the type of
daylight savings time correction to apply. The accepted values
are:
DST_NONE DST does not apply.
DST_USA USA DST correction.
DST_AUST Australian DST correction.
DST_WET Western European DST correction.
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gettimeofday(2)
DST_MET Middle European DST correction.
DST_EET Eastern European DST correction.
The current local time may be computed using the current time
zone by the following calculation:
local_usec = time_value->tv_usec;
local_sec = time_value->tv_sec - time_zone->tz_minuteswest * 60 +
(is_dst(time_value,time_zone) ? 60 * 60 : 0);
where is_dst(tv,tz) is some function that returns TRUE if
daylight savings time is currently in effect.
ACCESS CONTROL
None.
RETURN VALUE
0 Completed successfully.
-1 An error occurred. Errno is set to indicate the
error.
EXCEPTIONS
Errno may be set to one of the following error codes:
EFAULT An argument address referenced invalid memory.
SEE ALSO
The related manual sections: date(1),
settimeofday(2),
ctime(3).
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