man2/time.2

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   3 .\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
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  25 .\" Modified by Michael Haardt <michael@moria.de>
  26 .\" Modified Sat Jul 24 14:13:40 1993 by Rik Faith <faith@cs.unc.edu>
  27 .\" Additions by Joseph S. Myers <jsm28@cam.ac.uk>, 970909
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  29 .TH TIME 2 1997-09-09 "Linux 2.0.30" "Linux Programmer's Manual"
  30 .SH NAME
  31 time \- get time in seconds
  32 .SH SYNOPSIS
  33 .B #include <time.h>
  34 .sp
  35 .BI "time_t time(time_t *" t );
  36 .SH DESCRIPTION
  37 \fBtime\fP() returns the time since the Epoch
  38 (00:00:00 UTC, January 1, 1970), measured in seconds.
  39
  40 If
  41 .I t
  42 is non-NULL,
  43 the return value is also stored in the memory pointed to by
  44 .IR t .
  45 .SH "RETURN VALUE"
  46 On success, the value of time in seconds since the Epoch is returned.
  47 On error, ((time_t)\-1) is returned, and \fIerrno\fP is set
  48 appropriately.
  49 .SH ERRORS
  50 .TP
  51 .B EFAULT
  52 .I t
  53 points outside your accessible address space.
  54 .SH NOTES
  55 POSIX.1 defines
  56 .I seconds since the Epoch
  57 as a value to be interpreted as the number of seconds between a
  58 specified time and the Epoch, according to a formula for conversion
  59 from UTC equivalent to conversion on the naive basis that leap
  60 seconds are ignored and all years divisible by 4 are leap years.
  61 This value is not the same as the actual number of seconds between the time
  62 and the Epoch, because of leap seconds and because clocks are not
  63 required to be synchronised to a standard reference.
  64 The intention is
  65 that the interpretation of seconds since the Epoch values be
  66 consistent; see POSIX.1 Annex B 2.2.2 for further rationale.
  67 .SH "CONFORMING TO"
  68 SVr4, 4.3BSD, C89, C99, POSIX.1-2001.
  69 .\" .br
  70 .\" Under 4.3BSD, this call is obsoleted by
  71 .\" .BR gettimeofday (2).
  72 POSIX does not specify any error conditions.
  73 .SH "SEE ALSO"
  74 .BR date (1),
  75 .BR gettimeofday (2),
  76 .BR ctime (3),
  77 .BR ftime (3),
  78 .BR time (7)