Download youtube audio from ubuntu: adds artist and title as metadata and copies everything into /Music/<artist> folder. Supports both flv and mp4 formats.

yt2mp3.sh

#!/bin/bash
#Original script:
#http://www.linuxjournal.com/content/grabbing-your-music-youtube-do-it-your-way 
#modified to work with avconv
#Ubuntu >= 13.04: requires youtube-dl and the following packages:
#sudo apt-get install python-pip
#pip install youtube-dl
#sudo apt-get install libavcodec-extra-53 libav-tools
address=$1
regex='v=(.*)'
if [[ $address =~ $regex ]]; then
  video_id=${BASH_REMATCH[1]}
  video_id=$(echo $video_id | cut -d'&' -f1)
  video_title="$(youtube-dl --get-title $address)"
  youtube-dl --id $address
  ext="flv"
  if [ ! -f "$video_id"."$ext" ]; then
    ext="mp4"
  fi
  rxauthor_title='\s*(.+)\s+-\s*(.+)'
  if [[ $video_title =~ $rxauthor_title ]]; then
    author=${BASH_REMATCH[1]}
    title=${BASH_REMATCH[2]}
    avconv -i "$video_id"."$ext" -aq 256k -metadata title="$title" -metadata artist="$author" "$video_title".mp3
    if [ ! -d "$HOME"/Music/"$author" ]; then
      mkdir "$HOME"/Music/"$author"
    fi
    mv "$video_title".mp3 "$HOME"/Music/"$author"/"$title".mp3
  else
    avconv -i "$video_id"."$ext" -aq 256k "$video_title".mp3
    mv "$video_title".mp3 "$HOME"/Music/
  fi
  rm "$video_id"."$ext"
  echo 'done'
else
  echo "Sorry but the system encountered a problem." 
fi