Most versions of Linux use systemd to run services. As such you can use journalctl to show the logs.
Docker has its own logs and log viewing commands I think.
If you installed using the Debian/Ubuntu/Pi installation script then the command node-red-log
uses journalctl to display the log. If you did not install that way then something like sudo journalctl -f -n 50 -u nodered
should get you going.
Also they are written to /var/log/syslog, but mixed up with all the other system messages.