Running interface probe

Hi,
I would like to have an interface status probe: interface running → proble is ok; interface not running → probe failed

I created a probe like that:
name: Check_ether1
Type: function
Agent: default
Available: ros_command(“:put [interface ethernet get ether11 running]”)

but it does not work. I tried using the IF command, creating a dedicated function … but nothing!
How can I create a probe to check the status of an interface?

Thanks.