time - get time in seconds
time_t time(time_t *tloc);
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.
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
- tloc points outside your accessible address space (but see
SVr4, 4.3BSD, C89, C99, POSIX.1-2001. POSIX does not specify any error
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 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
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 reaches or exceeds
2**31 seconds (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.
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.
On some architectures, an implementation of time() is provided in the
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