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NAME

       time - get time in seconds

SYNOPSIS

       #include <time.h>

       time_t time(time_t *tloc);

DESCRIPTION

       time() returns the time as the number of seconds since the Epoch, 1970-01-01 00:00:00 +0000 (UTC).

       If tloc is non-NULL, the return value is also stored in the memory pointed to by tloc.

RETURN VALUE

       On  success,  the  value  of  time  in  seconds  since the Epoch is returned.  On error, ((time_t) -1) is
       returned, and errno is set appropriately.

ERRORS

       EFAULT tloc points outside your accessible address space (but see BUGS).

              On systems where the C library time() wrapper function invokes an implementation provided  by  the
              vdso(7)  (so  that  there  is  no  trap into the kernel), an invalid address may instead trigger a
              SIGSEGV signal.

CONFORMING TO

       SVr4, 4.3BSD, C89, C99, POSIX.1-2001.  POSIX does not specify any error conditions.

NOTES

       POSIX.1 defines seconds since the Epoch using a formula that approximates the number of seconds between a
       specified  time  and  the  Epoch.  This formula takes account of the facts that all years that are evenly
       divisible by 4 are leap years, but years that are evenly divisible by 100 are not leap years unless  they
       are  also  evenly divisible by 400, in which case they are leap years.  This value is not the same as the
       actual number of seconds between the time and the Epoch, because  of  leap  seconds  and  because  system
       clocks  are  not  required  to  be  synchronized  to  a  standard  reference.   The intention is that the
       interpretation of seconds since the Epoch values be consistent; see  POSIX.1-2008  Rationale  A.4.15  for
       further rationale.

       On Linux, a call to time() with tloc specified as NULL cannot fail with the error EOVERFLOW, even on ABIs
       where time_t is a signed 32-bit integer and the clock ticks past the time 2**31 (2038-01-19 03:14:08 UTC,
       ignoring  leap  seconds).   (POSIX.1 permits, but does not require, the EOVERFLOW error in the case where
       the seconds since the Epoch will not fit in time_t.)  Instead, the behavior on Linux  is  undefined  when
       the system time is out of the time_t range.  Applications intended to run after 2038 should use ABIs with
       time_t wider than 32 bits.

BUGS

       Error returns from this system call are indistinguishable from successful reports that the time is a  few
       seconds before the Epoch, so the C library wrapper function never sets errno as a result of this call.

       The  tloc  argument  is  obsolescent  and should always be NULL in new code.  When tloc is NULL, the call
       cannot fail.

SEE ALSO

       date(1), gettimeofday(2), ctime(3), ftime(3), time(7), vdso(7)

COLOPHON

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