.. zephyr:code-sample:: posix-gettimeofday
:name: gettimeofday() with clock initialization
Use ``gettimeofday()`` with clock initialization over SNTP.
Overview
********
This sample application demonstrates using the POSIX `gettimeofday()`_ function to display the
absolute wall clock time and local time every second. At system startup, the current time is
queried using the SNTP networking protocol, enabled by setting the
:kconfig:option:`CONFIG_NET_CONFIG_CLOCK_SNTP_INIT` and
:kconfig:option:`CONFIG_NET_CONFIG_SNTP_INIT_SERVER` options.
Requirements
************
- :ref:`networking_with_host`
- or, a board with hardware networking
- NAT/routing should be set up to allow connections to the Internet
- DNS server should be available on the host to resolve domain names
Building and Running
********************
This project outputs to the console. It can be built and executed on QEMU as follows:
.. zephyr-app-commands::
:zephyr-app: samples/posix/gettimeofday
:host-os: unix
:board: qemu_x86
:goals: run
:compact:
For comparison, to build directly for your host OS if it is POSIX compliant (for ex. Linux):
.. code-block:: console
cd samples/posix/gettimeofday
make -f Makefile.host
The make output file will be located in samples/posix/gettimeofday/build.
.. _gettimeofday(): https://pubs.opengroup.org/onlinepubs/009604599/functions/gettimeofday.html
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