Pour obtenir la diff des éléments entre deux listes :

To get the lines only in the old file:
comm -23 <(sort /tmp/oldList) <(sort /tmp/newList)

To get the lines only in the new file:
comm -13 <(sort /tmp/oldList) <(sort /tmp/newList)

comm -23 <(sort /tmp/1) <(sort /tmp/2)
comm -13 <(sort /tmp/1) <(sort /tmp/2)