How to trigger a Node-RED flow from a shell script

[Colin]

MQTT would work, but you would need an MQTT client installed on the PC, which you may not. curl may well already be installed, and is easily installed if it isn't, so possibly best to use that.

@HonestJohn61

presumably the IP would be that of the Node-RED server

Yes

@HonestJohn61

a particular port specified in both the curl request and Node-RED listening node

It would be the same port that node red uses (1880 by default). This post in the cookbook shows how you can easily create an http endpoint in node-red.

@HonestJohn61

does it matter that Node-RED will never respond to the curl request?

It will respond, as described in the example.