NAME

gettimeofday, settimeofday − get/set date and time

SYNOPSIS

#include <time.h>

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

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

HP-UX COMPATIBILITY

Level: HP-UX/STANDARD

Origin: UCB

DESCRIPTION

Gettimeofday returns the system’s notion of the current Greenwich time and the system’s notion of the current time zone.  Time returned is expressed relative 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 {
unsigned 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 (the value of the flag identifies the algorithm to be used for Daylight Saving time).  Programs should use this timezone information only in the absence of the TZ environment variable. 

Only the super-user may set the time of day. 

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 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. 

SEE ALSO

date(1), stime(2), time(2), ctime(3)

BUGS

The microsecond value usually has a granularity much greater than one due to the resolution of the system clock.  Depending on any granularity (particularly of one) will render code non-portable. 
 
 
 

Hewlett-Packard  —  last mod. May 11, 2021