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TIME(3) 		     Library Functions Manual			 TIME(3)

NAME
     time -- get time of day

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <time.h>

     time_t
     time(time_t *tloc);

DESCRIPTION
     The  time()  function returns the value of time in seconds since 0 hours, 0
     minutes, 0 seconds, January 1, 1970, Coordinated Universal Time (UTC).   If
     an error occurs, time() returns the value (time_t)-1.

     The return value is also stored in *tloc, provided that tloc is non-null.

ERRORS
     The time() function may fail for any of the reasons described in clock_get-
     time(2).

SEE ALSO
     clock_gettime(2), gettimeofday(2), ctime(3)

STANDARDS
     The time function conforms to IEEE Std 1003.1-2008 ("POSIX.1").

HISTORY
     The  time() system call first appeared in Version 1 AT&T UNIX.  Through the
     Version 3 AT&T UNIX, it returned 60 Hz ticks since an  epoch  that  changed
     occasionally,  because  it  was  a 32-bit value that overflowed in a little
     over 2 years.

     In Version 4 AT&T UNIX the granularity of the return value was  reduced  to
     whole seconds, delaying the aforementioned overflow until 2038.

     Version 7 AT&T UNIX introduced the ftime() system call, which returned time
     at a millisecond level, though retained the gtime() system call (exposed as
     time()  in  userland).   time()  could  have  been implemented as a wrapper
     around ftime(), but that wasn't done.

     4.1cBSD implemented a higher-precision time function gettimeofday() to  re-
     place ftime() and reimplemented time() in terms of that.

     Since  FreeBSD 9 the implementation of time() uses clock_gettime(CLOCK_SEC-
     OND) instead of gettimeofday() for performance reasons.

BUGS
     Neither ISO/IEC 9899:1999 ("ISO C99") nor IEEE Std 1003.1-2001  ("POSIX.1")
     requires  time() to set errno on failure; thus, it is impossible for an ap-
     plication to distinguish the valid time value -1 (representing the last UTC
     second of 1969) from the error return value.

     Systems conforming to earlier versions of the C and  POSIX  standards  (in-
     cluding older versions of FreeBSD) did not set *tloc in the error case.

FreeBSD ports 15.quarterly	 April 14, 2022 			 TIME(3)

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