135 lines
4.3 KiB
Groff
135 lines
4.3 KiB
Groff
.\" Copyright (c) 1980, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the University of
|
|
.\" California, Berkeley and its contributors.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)gettimeofday.2 8.2 (Berkeley) 5/26/95
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd May 26, 1995
|
|
.Dt GETTIMEOFDAY 2
|
|
.Os BSD 4
|
|
.Sh NAME
|
|
.Nm gettimeofday ,
|
|
.Nm settimeofday
|
|
.Nd get/set date and time
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.Fd #include <sys/time.h>
|
|
.Ft int
|
|
.Fn gettimeofday "struct timeval *tp" "struct timezone *tzp"
|
|
.Ft int
|
|
.Fn settimeofday "const struct timeval *tp" "const struct timezone *tzp"
|
|
.Sh DESCRIPTION
|
|
.Bf -symbolic
|
|
Note: timezone is no longer used; this information is kept outside
|
|
the kernel.
|
|
.Ef
|
|
.Pp
|
|
The system's notion of the current Greenwich time and the current time
|
|
zone is obtained with the
|
|
.Fn gettimeofday
|
|
call, and set with the
|
|
.Fn settimeofday
|
|
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
|
|
.Dq ticks .
|
|
If
|
|
.Fa tp
|
|
or
|
|
.Fa tzp
|
|
is NULL, the associated time
|
|
information will not be returned or set.
|
|
.Pp
|
|
The structures pointed to by
|
|
.Fa tp
|
|
and
|
|
.Fa tzp
|
|
are defined in
|
|
.Ao Pa sys/time.h Ac
|
|
as:
|
|
.Pp
|
|
.Bd -literal
|
|
struct timeval {
|
|
long tv_sec; /* seconds since Jan. 1, 1970 */
|
|
long tv_usec; /* and microseconds */
|
|
};
|
|
|
|
struct timezone {
|
|
int tz_minuteswest; /* minutes west of Greenwich */
|
|
int tz_dsttime; /* type of dst correction */
|
|
};
|
|
.Ed
|
|
.Pp
|
|
The
|
|
.Fa 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.
|
|
.Pp
|
|
Only the super-user may set the time of day or time zone.
|
|
If the system is running in secure mode (see
|
|
.Xr init 8 ) ,
|
|
the time may only be advanced.
|
|
This limitation is imposed to prevent a malicious super-user
|
|
from setting arbitrary time stamps on files.
|
|
The system time can still be adjusted backwards using the
|
|
.Xr adjtime 2
|
|
system call even when the system is secure.
|
|
.Sh RETURN VALUES
|
|
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
|
|
.Va errno .
|
|
.Sh ERRORS
|
|
The following error codes may be set in
|
|
.Va errno :
|
|
.Bl -tag -width Er
|
|
.It Bq Er EFAULT
|
|
An argument address referenced invalid memory.
|
|
.It Bq Er EPERM
|
|
A user other than the super-user attempted to set the time.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr date 1 ,
|
|
.Xr adjtime 2 ,
|
|
.Xr ctime 3 ,
|
|
.Xr clocks 7 ,
|
|
.Xr timed 8
|
|
.Sh HISTORY
|
|
The
|
|
.Fn gettimeofday
|
|
function call appeared in
|
|
.Bx 4.2 .
|