NAME

       time - get time in seconds

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <time.h>

       time_t time(time_t *_Nullable 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 to indicate the error.

ERRORS

       EOVERFLOW
              The time cannot be represented as a time_t value.  This can happen if an executable
              with 32-bit time_t is run on a 64-bit kernel when the time is  2038-01-19  03:14:08
              UTC  or  later.   However,  when  the  system  time is out of time_t range in other
              situations, the behavior is undefined.

       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.

VERSIONS

       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.  Linux systems  normally  follow  the
       POSIX  requirement  that  this  value  ignore  leap  seconds,  so  that conforming systems
       interpret it consistently; see POSIX.1-2018 Rationale A.4.16.

       Applications intended to run after 2038 should use ABIs with time_t wider  than  32  bits;
       see time_t(3type).

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

STANDARDS

       C11, POSIX.1-2008.

HISTORY

       SVr4, 4.3BSD, C89, POSIX.1-2001.

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)