time() C99 compliance:
[dragonfly.git] / lib / libc / gen / time.3
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32.\" @(#)time.3 8.1 (Berkeley) 6/4/93
fa69c81b 33.\" $FreeBSD: src/lib/libc/gen/time.3,v 1.15 2007/01/09 00:27:55 imp Exp $
1de703da 34.\" $DragonFly: src/lib/libc/gen/time.3,v 1.2 2003/06/17 04:26:42 dillon Exp $
984263bc 35.\"
fa69c81b 36.Dd July 18, 2003
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37.Dt TIME 3
38.Os
39.Sh NAME
40.Nm time
41.Nd get time of day
42.Sh LIBRARY
43.Lb libc
44.Sh SYNOPSIS
45.In time.h
46.Ft time_t
47.Fn time "time_t *tloc"
48.Sh DESCRIPTION
49The
50.Fn time
51function
52returns the value of time in seconds since 0 hours, 0 minutes,
530 seconds, January 1, 1970, Coordinated Universal Time.
fa69c81b 54If an error occurs,
984263bc 55.Fn time
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56returns the value
57.Po Vt time_t Pc Ns \-1 .
58.Pp
59The return value is also stored in
60.No \&* Ns Va tloc ,
61provided that
62.Va tloc
63is non-null.
984263bc 64.Sh ERRORS
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65The
66.Fn time
67function may fail for any of the reasons described in
68.Xr gettimeofday 2 .
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69.Sh SEE ALSO
70.Xr gettimeofday 2 ,
71.Xr ctime 3
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72.Sh STANDARDS
73The
74.Nm
75function conforms to
76.St -p1003.1-2001 .
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77.Sh HISTORY
78A
79.Fn time
80function appeared in
81.At v6 .
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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.