Here below are some applications for Linux that I run almost daily from the terminal. I hope you'll find them useful too.

Ecasound

Sound recording; lately I am in the process of transferring my cassete tapes to mp3. I used to use Audacity, but it just takes too much processing power. Now I use ecasound.

to install the set of useful apps (providing Pulse Audio is the background sound handler)

sudo apt-get install ecasound gnome-alsamixer pavumeter

To start Ecasound, use:

ecasound -i alsa -o somefile.mp3 -c

So now, with a few keyboard shortcuts you can manupulate the program

t - Start recording
s - Stop recording
h - help
q - Quit ecasound

If you are not getting any sound, use gnome-alsamixer to tweak the inputs and outputs as well as recording levels of your soundcard.
Use pavumeter --record to get the Pulse Audio metering of the recording levels.