Node-red flow to shutdown Pi error 127

Hi folks,
First post here, total noob to home assistant, node-red and Pi. Wish me luck!
I’m running the latest versions of everything, installed only a few days ago.

I’m wanting to implement a physical safe shutdown button on the Pi that triggers a node-red flow to send the command.
My proof-of-concept flow is simple: inject (payload:string:1) --> exec (command: sudo shutdown -h now). (Later development will read a GPIO pin for the trigger.)
Payload is not appended anywhere.

I get an error:127

Debugging the exec outputs shows:
stderr: /bin/sh: shutdown: not found
return code: Command failed: shutdown -h now
/bin/sh: shutdown: not found

So what’s the correct command to send? Or where do I find the shutdown command if it’s not in /bin/sh ?