Удаление устаревших ядер linux

 dpkg -l linux-* | awk '/^ii/{ print $2}' | grep -v -e `uname -r | cut -f1,2 -d"-"` | grep -e [0-9] | grep -E "(image|headers)" | xargs sudo apt-get -y purge

 http://tuxtweaks.com/2010/10/remove-old-kernels-in-ubuntu-with-one-command/