Section: Linux Programmer's Manual (2)
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time - get time in seconds
time_t time(time_t *tloc);
returns the time as the number of seconds since the
Epoch, 1970-01-01 00:00:00 +0000 (UTC).
the return value is also stored in the memory pointed to by
On success, the value of time in seconds since the Epoch is returned.
On error, ((time_t) -1) is returned, and errno is set
points outside your accessible address space (but see BUGS).
On systems where the C library
wrapper function invokes an implementation provided by the
(so that there is no trap into the kernel),
an invalid address may instead trigger a
SVr4, 4.3BSD, C89, C99, POSIX.1-2001.
POSIX does not specify any error conditions.
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
specified as NULL cannot fail with the error
even on ABIs where
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
error in the case where the seconds since the Epoch will not fit in
Instead, the behavior on Linux is undefined when the system time is out of the
Applications intended to run after 2038 should use ABIs with
wider than 32 bits.
Error returns from this system call are indistinguishable from
successful reports that the time is a few seconds
the Epoch, so the C library wrapper function never sets
as a result of this call.
argument is obsolescent and should always be NULL in new code.
is NULL, the call cannot fail.
C library/kernel differences
On some architectures, an implementation of
is provided in the
This page is part of release 4.15 of the Linux
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
- RETURN VALUE
- CONFORMING TO
- C library/kernel differences
- SEE ALSO
This document was created by
using the manual pages.
Time: 02:04:14 GMT, September 25, 2018