.\" Copyright (c) 1980 The Regents of the University of California. .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms are permitted provided .\" that: (1) source distributions retain this entire copyright notice and .\" comment, and (2) distributions including binaries display the following .\" acknowledgement: ``This product includes software developed by the .\" University of California, Berkeley and its contributors'' in the .\" documentation or other materials provided with the distribution and in .\" all advertising materials mentioning features or use of this software. .\" 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED .\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. .\" .\" @(#)gettimeofday.2 6.10 (Berkeley) 6/23/90 .\" .TH GETTIMEOFDAY 2 "June 23, 1990" .UC 4 .SH NAME gettimeofday, settimeofday \- get/set date and time .SH SYNOPSIS .nf .ft B #include <sys/time.h> .PP .ft B gettimeofday(tp, tzp) struct timeval *tp; struct timezone *tzp; .PP .ft B settimeofday(tp, tzp) struct timeval *tp; struct timezone *tzp; .fi .SH DESCRIPTION The system's notion of the current Greenwich time and the current time zone is obtained with the \fIgettimeofday\fP call, and set with the \fIsettimeofday\fP 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 \fItp\fP or \fItzp\fP is NULL, the associated time information will not be returned or set. .PP The structures pointed to by .I tp and .I tzp are defined in .I <sys/time.h> as: .PP .nf .RS .DT struct timeval { long tv_sec; /* seconds since Jan. 1, 1970 */ long tv_usec; /* and microseconds */ }; .sp 1 struct timezone { int tz_minuteswest; /* of Greenwich */ int tz_dsttime; /* type of dst correction to apply */ }; .RE .fi .PP The .I 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. .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 \fIerrno\fP. .SH "ERRORS The following error codes may be set in \fIerrno\fP: .TP 15 [EFAULT] An argument address referenced invalid memory. .TP 15 [EPERM] A user other than the super-user attempted to set the time. .SH "SEE ALSO" date(1), adjtime(2), ctime(3), timed(8)