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.Dd $Mdocdate: December 11 2021 $
.Dt TIME 3
.Os
.Sh NAME
.Nm time
.Nd get time of day
.Sh SYNOPSIS
.In time.h
.Ft time_t
.Fn time "time_t *now"
.Sh DESCRIPTION
The
.Fn time
function returns the number of seconds elapsed since
Jan 1 1970 00:00:00 UTC.
This value is also written to
.Fa now
unless
.Fa now
is
.Dv NULL .
.Sh RETURN VALUES
The
.Fn time
function is always successful,
and no return value is reserved to indicate an error.
.Sh SEE ALSO
.Xr clock_gettime 2 ,
.Xr gettimeofday 2 ,
.Xr ctime 3
.Sh STANDARDS
The
.Fn time
function conforms to
.St -p1003.1-2008 .
.Sh HISTORY
A
.Fn time
system call first appeared in
.At v1 .
That version counted time in sixtieths of a second with a 32-bit return value,
ensuring an integer overflow crisis every 2.26 years.
In
.At v6
the granularity of the return value was reduced to whole seconds,
delaying the aforementioned crisis until 2038.
In
.Bx 4.1c
the function was moved out of the kernel into the C standard library and
reimplemented with
.Xr gettimeofday 2 .