import prefect
from prefect import Task
from prefect import task, Flow, Parameter
from prefect.tasks.shell import ShellTask

shell_task = ShellTask(
    helper_script="",
    shell="bash",
    log_stderr=True,
    return_all=True,
    stream_output=True,
)

@task
def get_command(param):
    return f"echo '{param}'"

with Flow(name="Test") as flow:
    param = Parameter('param')
    cmd = get_command(param)
    test = shell_task(command=cmd)

flow.run(parameters=dict(param='a'))

Rscript file.R

shell_task = ShellTask(
    helper_script="",
    shell="bash",
    log_stderr=True,
    return_all=True,
    stream_output=True,
)
with Flow(name="Test") as flow:
    test = shell_task(command="echo 'test'")