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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 $
37 .Nd get/set date and time
43 .Fn gettimeofday "struct timeval *tp" "struct timezone *tzp"
45 .Fn settimeofday "const struct timeval *tp" "const struct timezone *tzp"
52 functions are obsolescent.
53 Applications should use the
60 The system's notion of the current Greenwich time and the current time
61 zone is obtained with the
63 call, and set with the
65 call. The time is expressed in seconds and microseconds
66 since midnight (0 hour), January 1, 1970. The resolution of the system
67 clock is hardware dependent, and the time may be updated continuously or
74 is NULL, the associated time
75 information will not be returned or set.
77 The structures pointed to by
86 long tv_sec; /* seconds since Jan. 1, 1970 */
87 long tv_usec; /* and microseconds */
91 int tz_minuteswest; /* minutes west of Greenwich */
92 int tz_dsttime; /* type of dst correction */
98 structure indicates the local time zone
99 (measured in minutes of time westward from Greenwich),
100 and a flag that, if nonzero, indicates that
101 Daylight Saving time applies locally during
102 the appropriate part of the year.
104 Only the super-user may set the time of day or time zone.
105 If the system is running at securelevel \(>= 2 (see
107 the time may only be advanced or retarded by a maximum of one second.
108 This limitation is imposed to prevent a malicious super-user
109 from setting arbitrary time stamps on files.
110 The system time can be adjusted backwards without restriction using the
112 system call even when the system is secure.
116 The following error codes may be set in
120 An argument address referenced invalid memory.
122 A user other than the super-user attempted to set the time.
132 function call appeared in