Thanks guys. Swapping out '-c- with '--server-settings' did the trick. I knew it had to be something obvious like that.

I have a rather perplexing issue with my server-settings.json file. Whenever I try starting the server using the file, I get the following error:

$ sudo -u factorio /opt/factorio/bin/x64/factorio -c /opt/factorio/data/server-settings.json --start-server-load-latest –Port 64444
0.000 Error ...