combine

apt-get install moreutils
ssh host1 dpkg --get-selections > dpkg.out.1
ssh host2 dpkg --get-selections > dpkg.out.2
combine dpkg.out.1 not dpkg.out.2 # ami fent van a host1-en, de nincs a host2-on

forrás: http://hup.hu/node/11113#comment-731141