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+.\" 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 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
+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 [EFAULT]
+.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 .