GETTIMEOFDAY

Section: Linux Programmer's Manual (2)
Updated: 15 April 1995
Index Return to Main Contents
 

NAME

gettimeofday, settimeofday - get / set time  

SYNOPSIS

#include <sys/time.h>
#include <unistd.h>

int gettimeofday(struct timeval *tv, struct timezone *tz);
int settimeofday(const struct timeval *tv , const struct timezone *tz);  

DESCRIPTION

gettimeofday and settimeofday can set the time as well as a timezone. tv is a timeval struct, as specified in /usr/include/sys/time.h:

struct timeval {
long    tv_sec;         /* seconds */
long    tv_usec;        /* microseconds */
};

and tz is a timezone :

struct timezone {
int     tz_minuteswest;
/* minutes west of Greenwich */
int     tz_dsttime;
/* type of dst correction */
};

With daylight savings times defined as follows :

DST_NONE /* not on dst */
DST_USA         /* USA style dst */

DST_AUST        /* Australian style dst */

DST_WET /* Western European dst */
DST_MET /* Middle European dst */
DST_EET /* Eastern European dst */
DST_CAN /* Canada */
DST_GB  /* Great Britain and Eire */

DST_RUM /* Rumania */
DST_TUR /* Turkey */
DST_AUSTALT     /* Australian style with shift in 1986 */

And the following macros are defined to operate on this :

#define timerisset(tvp)\

                  ((tvp)->tv_sec || (tvp)->tv_usec) #define timercmp(tvp, uvp, cmp)\ ((tvp)->tv_sec cmp (uvp)->tv_sec ||\ (tvp)->tv_sec == (uvp)->tv_sec &&\ (tvp)->tv_usec cmp (uvp)->tv_usec) #define timerclear(tvp)
                  ((tvp)->tv_sec = (tvp)->tv_usec = 0)

If either tv or tz is null, the corresponding structure is not set or returned.

Only the super user may use settimeofday.  

ERRORS

EPERM
settimeofday is called by someone other than the superuser.
EINVAL
Timezone (or something else) is invalid.
 

CONFORMING TO

BSD 4.3  

SEE ALSO

date(1), adjtimex(2), time(2), ctime(3), ftime(3)


 

Index

NAME
SYNOPSIS
DESCRIPTION
ERRORS
CONFORMING TO
SEE ALSO

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