[Mon Jun 01 14:24:57] whatvn@osvn:~$ longurl='</span></p> from; http://futurebrain.free.fr/audio/Party%20All%20The%20Time.mp3</span></p>'

whatvn@osvn:~$ sed 's/..................//' $longurl
sed: can't read </span></p>: No such file or directory
sed: can't read from;: No such file or directory
sed: can't read http://futurebrain.free.fr/audio/Party%20All%20The%20Time.mp3</span></p>: No such file or directory

[Mon Jun 01 14:42:25] whatvn@osvn:~$ sed 's/...........$//' url | sed 's/..................//' 
 http://futurebrain.free.fr/audio/Party%20All%20The%20Time.mp3

$ a='abcdefghi'
$ echo $a | sed 's/a/b/'
bbcdefghi

echo $longurl | sed 'pattern'

sed [OPTION]... {script-only-if-no-other-script} [input-file]...

$ echo $longurl | sed 's/<\/span><\/p> from; //' | sed 's/<\/span><\/p>//'

$ echo $longurl | awk -F "; " '{ print $2 }' | awk -F "</span>" '{ print $1 }'