NAME
settimeofday() — set the date and time
SYNOPSIS
#include <sys/time.h>
int settimeofday struct timeval *tp, const struct timezone *tzp);
DESCRIPTION
The
settimeofday()
function sets the current time, expressed as seconds and
microseconds since Epoch, and passed as the
timeval
structure pointed to by
tp.
The resolution of the system clock is one microsecond.
Security Restrictions
Setting the time of day requires the
PRIV_SYSATTR
privilege (SYSATTR).
Processes owned by the superuser will have this privilege.
Processes owned by other users may have this privilege, depending on system
configuration. See
privileges(5)
for more information about privileged access on
systems that support fine-grained privileges.
Only a user with appropriate privileges can set the time
of day.
PARAMETERS
- tp
A pointer to a
timeval
structure in which the current time is returned.
The
timeval
structure includes the following members:
time_t tv_sec /* Seconds. */
long tv_usec /* Microseconds. */
- tzp
If this parameter is not a null pointer, it is interpreted as a
pointer to a
timezone
structure under HP-UX.
The
timezone
structure has the following fields:
- tz_minuteswest
The number of minutes that the local time zone is
west of Coordinated Universal Time (UTC) or Epoch.
- tz_dsttime
A flag that, if nonzero, indicates that Daylight
Savings Time (DST) applies locally during the
appropriate part of the year.
RETURN VALUE
gettimeofday()
returns the following values under HP-UX:
- 0
Successful completion.
- -1
Failure.
errno
is set to indicate the error.
ERRORS
If
gettimeofday()
fails,
errno
is set to the following value under HP-UX:
- [EFAULT]
An argument address referenced invalid memory.
- [EINVAL]
The
tv_sec
member of the tp parameter to
settimeofday()
was less than zero or greater than 2^31.
- [EPERM]
A user lacking appropriate privileges attempted to
set the time.
WARNINGS
Relying on a granularity of one microsecond may result in code
that is not portable to other platforms.
AUTHOR
settimeofday()
was developed by the University of California,
Berkeley, and HP.
