1.\" Copyright (c) 1980, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)gettimeofday.2 8.2 (Berkeley) 5/26/95 29.\" $FreeBSD: src/lib/libc/sys/gettimeofday.2,v 1.9.2.9 2003/02/11 06:05:00 nsayer Exp $ 30.\" 31.Dd March 26, 2016 32.Dt GETTIMEOFDAY 2 33.Os 34.Sh NAME 35.Nm gettimeofday , 36.Nm settimeofday 37.Nd get/set date and time 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In sys/time.h 42.Ft int 43.Fn gettimeofday "struct timeval *tp" "struct timezone *tzp" 44.Ft int 45.Fn settimeofday "const struct timeval *tp" "const struct timezone *tzp" 46.Sh DESCRIPTION 47.Bf -symbolic 48Note: The 49.Fn gettimeofday 50and 51.Fn settimeofday 52functions are obsolescent. 53Applications should use the 54.Fn clock_gettime 55and 56.Fn clock_settime 57functions instead. 58.Ef 59.Pp 60The system's notion of the current Greenwich time and the current time 61zone is obtained with the 62.Fn gettimeofday 63call, and set with the 64.Fn settimeofday 65call. The time is expressed in seconds and microseconds 66since midnight (0 hour), January 1, 1970. The resolution of the system 67clock is hardware dependent, and the time may be updated continuously or 68in 69.Dq ticks . 70If 71.Fa tp 72or 73.Fa tzp 74is NULL, the associated time 75information will not be returned or set. 76.Pp 77The structures pointed to by 78.Fa tp 79and 80.Fa tzp 81are defined in 82.In sys/time.h 83as: 84.Bd -literal 85struct timeval { 86 long tv_sec; /* seconds since Jan. 1, 1970 */ 87 long tv_usec; /* and microseconds */ 88}; 89 90struct timezone { 91 int tz_minuteswest; /* minutes west of Greenwich */ 92 int tz_dsttime; /* type of dst correction */ 93}; 94.Ed 95.Pp 96The 97.Fa timezone 98structure indicates the local time zone 99(measured in minutes of time westward from Greenwich), 100and a flag that, if nonzero, indicates that 101Daylight Saving time applies locally during 102the appropriate part of the year. 103.Pp 104Only the super-user may set the time of day or time zone. 105If the system is running at securelevel \(>= 2 (see 106.Xr init 8 ) , 107the time may only be advanced or retarded by a maximum of one second. 108This limitation is imposed to prevent a malicious super-user 109from setting arbitrary time stamps on files. 110The system time can be adjusted backwards without restriction using the 111.Xr adjtime 2 112system call even when the system is secure. 113.Sh RETURN VALUES 114.Rv -std 115.Sh ERRORS 116The following error codes may be set in 117.Va errno : 118.Bl -tag -width Er 119.It Bq Er EFAULT 120An argument address referenced invalid memory. 121.It Bq Er EPERM 122A user other than the super-user attempted to set the time. 123.El 124.Sh SEE ALSO 125.Xr date 1 , 126.Xr adjtime 2 , 127.Xr ctime 3 , 128.Xr clocks 7 , 129.Xr timed 8 130.Sh HISTORY 131The 132.Fn gettimeofday 133function call appeared in 134.Bx 4.2 . 135