xref: /freebsd/lib/libc/gen/time.3 (revision 8fc257994d0ce2396196d7a06d50d20c8015f4b7)
1.\" Copyright (c) 1989, 1991, 1993
2.\"	The Regents of the University of California.  All rights reserved.
3.\"
4.\" This code is derived from software contributed to Berkeley by
5.\" the American National Standards Committee X3, on Information
6.\" Processing Systems.
7.\"
8.\" Redistribution and use in source and binary forms, with or without
9.\" modification, are permitted provided that the following conditions
10.\" are met:
11.\" 1. Redistributions of source code must retain the above copyright
12.\"    notice, this list of conditions and the following disclaimer.
13.\" 2. Redistributions in binary form must reproduce the above copyright
14.\"    notice, this list of conditions and the following disclaimer in the
15.\"    documentation and/or other materials provided with the distribution.
16.\" 4. Neither the name of the University nor the names of its contributors
17.\"    may be used to endorse or promote products derived from this software
18.\"    without specific prior written permission.
19.\"
20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30.\" SUCH DAMAGE.
31.\"
32.\"     @(#)time.3	8.1 (Berkeley) 6/4/93
33.\" $FreeBSD$
34.\"
35.Dd July 18, 2003
36.Dt TIME 3
37.Os
38.Sh NAME
39.Nm time
40.Nd get time of day
41.Sh LIBRARY
42.Lb libc
43.Sh SYNOPSIS
44.In time.h
45.Ft time_t
46.Fn time "time_t *tloc"
47.Sh DESCRIPTION
48The
49.Fn time
50function
51returns the value of time in seconds since 0 hours, 0 minutes,
520 seconds, January 1, 1970, Coordinated Universal Time.
53If an error occurs,
54.Fn time
55returns the value
56.Po Vt time_t Pc Ns \-1 .
57.Pp
58The return value is also stored in
59.No \&* Ns Va tloc ,
60provided that
61.Va tloc
62is non-null.
63.Sh ERRORS
64The
65.Fn time
66function may fail for any of the reasons described in
67.Xr gettimeofday 2 .
68.Sh SEE ALSO
69.Xr clock_gettime 2 ,
70.Xr gettimeofday 2 ,
71.Xr ctime 3
72.Sh STANDARDS
73The
74.Nm
75function conforms to
76.St -p1003.1-2001 .
77.Sh HISTORY
78A
79.Fn time
80function appeared in
81.At v6 .
82.Sh BUGS
83Neither
84.St -isoC-99
85nor
86.St -p1003.1-2001
87requires
88.Fn time
89to set
90.Va errno
91on failure; thus, it is impossible for an application to distinguish
92the valid time value \-1 (representing the last UTC second of 1969)
93from the error return value.
94.Pp
95Systems conforming to earlier versions of the C and
96.Tn POSIX
97standards (including older versions of
98.Fx )
99did not set
100.No \&* Ns Va tloc
101in the error case.
102