Ubuntu Server 并无桌面环境，多次升级以后系统中会存在大量不同版本的内核，而每个内核占用非常多的硬盘空间（一般一个内核300mb左右占用），所以需要定期清理没用的内核。
1.查看当前使用的时哪个内核.
magth@cloud:~$ uname -a Linux cloud 4.4.0-96-generic #119-Ubuntu SMP Tue Sep 12 14:59:54 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
2.查看当前系统安装了多少内核
magth@magth:~$ dpkg --get-selections|grep linux console-setup-linux install libselinux1:amd64 install linux-base install linux-firmware install linux-generic install linux-headers-4.4.0-62 install linux-headers-4.4.0-62-generic install linux-headers-4.4.0-92 install linux-headers-4.4.0-92-generic install linux-headers-4.4.0-93 install linux-headers-4.4.0-93-generic install linux-headers-4.4.0-96 install linux-headers-4.4.0-96-generic install linux-headers-generic install linux-image-4.4.0-62-generic install linux-image-4.4.0-92-generic install linux-image-4.4.0-93-generic install linux-image-4.4.0-96-generic install linux-image-extra-4.4.0-62-generic install linux-image-extra-4.4.0-92-generic install linux-image-extra-4.4.0-93-generic install linux-image-extra-4.4.0-96-generic install linux-image-generic install linux-libc-dev:amd64 install util-linux install
3.一键清理多余内核命令
magth@magth:~$ dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d' | xargs sudo apt-get -y purge
4.内核清理完毕
magth@cloud:~$ dpkg --get-selections|grep linux console-setup-linux install libselinux1:amd64 install linux-base install linux-firmware install linux-generic install linux-headers-4.4.0-96 install linux-headers-4.4.0-96-generic install linux-headers-generic install linux-image-4.4.0-96-generic install linux-image-extra-4.4.0-96-generic install linux-image-generic install linux-libc-dev:amd64 install util-linux install
4.还有一种情况，系统内核已经卸载了，但是并未实际删除显示状态为 deinstall ，清理命令为：
magth@cloud:~$ dpkg --get-selections | grep deinstall | sed 's/deinstall/\lpurge/' | sudo dpkg --set-selections; sudo dpkg -Pa
Categories: ubuntu
