.\"	$NetBSD: time.3,v 1.16 2011/11/05 18:17:29 christos Exp $
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.\"     @(#)time.3	8.1 (Berkeley) 6/4/93
.\"
.Dd November 5, 2011
.Dt TIME 3
.Os
.Sh NAME
.Nm time
.Nd get time of day
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In time.h
.Ft time_t
.Fn time "time_t *tloc"
.Sh DESCRIPTION
The
.Fn time
function
returns the value of time in seconds since 0 hours, 0 minutes,
0 seconds, January 1, 1970, Coordinated Universal Time.
.Pp
A copy of the time value may be saved to the area indicated by the
pointer
.Fa tloc .
If
.Fa tloc
is a
.Dv NULL
pointer, no value is stored.
.Pp
Upon successful completion,
.Fn time
returns the value of time.
Otherwise a value of
.Po
.Po Fa time_t Pc \-1
.Pc
is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
No errors are defined.
.Sh SEE ALSO
.Xr gettimeofday 2 ,
.Xr ctime 3
.Sh STANDARDS
The
.Fn time
function conforms to
.St -p1003.1-90 .
.Sh HISTORY
A
.Fn time
function appeared in
.At v2 .
It returned a 32-bit value measuring sixtieths of a second, leading to
rollover every 2.26 years.
In
.At v6 ,
the precision of
.Fn time
was changed to seconds, allowing 135.6 years between rollovers.
.Pp
In
.Nx 6.0
the
.Vt time_t
type was changed to be 64 bits wide, including on 32-bit machines,
making rollover a concern for the far distant future only.
Note however that any code making the incorrect assumption that
.Vt time_t
is the same as
.Vt long
will fail on 32-bit machines in 2038.