Found it with:
sudo tail /var/log/redis/redis-server.log -n 100
So if the setup was more standard that should be:
sudo tail /var/log/redis_6379.log -n 100
This outputs the last 100 lines of the file.
Where your log file is located is in your configs that you can access with:
redis-cli CONFIG GET *
The log file may not always be shown using the above. In that case use
tail -f `less /etc/redis/redis.conf | grep logfile|cut -d\ -f2`