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.

   C library/kernel differences
       On some architectures, an implementation of time() is provided in the vdso(7).

SEE ALSO

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

COLOPHON

       This page is part of release 5.10 of  the  Linux  man-pages  project.   A  description  of  the  project,
       information   about   reporting   bugs,   and   the  latest  version  of  this  page,  can  be  found  at
       https://www.kernel.org/doc/man-pages/.

Linux                                              2017-09-15                                            TIME(2)