Datetime Cycling

Get a copy of this example

$ cylc get-resources examples/datetime-cycling

[meta]
    title = Datetime Cycling
    description = """
        A basic cycling workflow which runs the same set of tasks over
        and over. Each cycle will be given a datetime identifier.

        The task "a" will wait until the real-world (or wallclock) time passes
        the cycle time.

        Try changing the "initial cycle point" to "previous(00T00) - P1D" to
        see how this works.
    """

[scheduling]
    # set the start of the graph to 00:00 this morning
    initial cycle point = previous(T00)

    [[graph]]
        # repeat this with a "P"eriod of "1" "D"ay -> P1D
        P1D = """
            # this is the workflow we want to repeat:
            a => b => c & d

            # this is an "inter-cycle dependency", it makes the task "b"
            # wait until its previous instance has successfully completed:
            b[-P1D] => b

            # this makes the task "a" wait until its cycle point matches
            # the real world time - i.e. it prevents the workflow from getting
            # ahead of the clock. If the workflow is running behind (e.g. after
            # a delay, or from an earlier initial cycle point) it will catch
            # until the clock-trigger constrains it again. To run entirely in
            # "simulated time" remove this line:
            @wall_clock => a
        """

[runtime]
    [[root]]
        # all tasks will "inherit" the configuration in the "root" section
        script = echo "Hello, I'm task $CYLC_TASK_NAME in cycle $CYLC_TASK_CYCLE_POINT!"
    [[a]]
    [[b]]
    [[c]]
    [[d]]

Run it with:

$ cylc vip datetime-cycling