recording with Audacity
 

I would like to record audio off a DVD (played in my DVD drive) using Audacity. So...I guess just pressing the record button while the DVD plays doesn't do it, because after I stopped the DVD, stopped recording, and played the recording back, it played no sound and didn't seem to have recorded any. What else do I have to do? I'm new to not only Audacity but the entire process of recording audio from anything. (Someone had to explain to me that I don't need a separate audio cable for the DVD drive because audio goes through the SATA cable.)

not sure why that doesnt work but it may be that your specific soundcard is incapable of playing and recording at the same time ?

something like this mite work:

Possibly. I have only the internal audio (sound card?) that came with the motherboard. (I thought I needed a separate sound card to make a good audio recording, but someone said not necessarily. So I'll first see how good a recording my onboard audio can make.)

What is the command you suggest supposed to do?--record from the CLI, or analyze why I can't record?

just so you are aware the above command (and others like it ffmpeg , mplayer -dumpaudio , ...) are digitally converting the audio rather than doing a real-time recording. if you really want to record try plugging in a mic and run arecord (you mite need to run alsmixer and make sure all the proper channels are unmuted).

Re-recording in Audacity
 

I believe you'll need to 'Import' the file into Audacity. Once it's loaded into Audacity then you can 'play' with it.

Thanks, that was what I needed. I wanted to capture to a computer audio that was already on a DVD.