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GETTIMEOFDAY(2) | System Calls Manual | GETTIMEOFDAY(2) |
NAME¶
gettimeofday
,
settimeofday
—
get/set date and time
LIBRARY¶
Standard C Library (libc, -lc)SYNOPSIS¶
#include
<sys/time.h>
int
gettimeofday
(struct
timeval *tp,
struct timezone
*tzp);
int
settimeofday
(const
struct timeval *tp,
const struct timezone
*tzp);
DESCRIPTION¶
Note: timezone is no longer used; this information is kept
outside the kernel.
The system's notion of the current Greenwich time and the current time zone is
obtained with the gettimeofday
() system
call, and set with the settimeofday
()
system 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 tp or
tzp is NULL, the associated time information
will not be returned or set.
The structures pointed to by tp and
tzp are defined in
<sys/time.h>
as:
struct timeval { time_t tv_sec; /* seconds */ suseconds_t tv_usec; /* and microseconds */ }; struct timezone { int tz_minuteswest; /* minutes west of Greenwich */ int tz_dsttime; /* type of dst correction */ };
RETURN VALUES¶
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.ERRORS¶
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), adjtime(2), clock_gettime(2), ctime(3), timeradd(3), clocks(7), timed(8)HISTORY¶
Thegettimeofday
() system call appeared in
4.2BSD.May 26, 1995 | Debian |