I have an Arduino Uno and whenever I connect it to my computer, the power light turns on and everything seems to be running, except I can't find the correct serial port in the tools menu. At one point, it was there for about a minute before it went away again, so i'm not entirely sure what's happening. I read the troubleshooting page on this but I don't know how to check for any of the things it's telling me to do (check for programs that run all serial ports, make sure firewalls aren't blocking the serial ports, etc.) I'm fairly new to the whole thing, so i'm hoping someone can help me figure out what the problem is.
I forgot to mention before, i'm on a macbook air, OS X version 10.9.5
Sorry if this all sounds really stupid. I'm completely new to Arduino and am not technologically savvy in the least.
Bring up a terminal window and run dmesg without it plugged in, plug it in, count to 20 and run it again and see what extra output you get.