root权限下执行下面命令：
wget -O - https://github.com/OpenMediaVault-Plugin-Developers/packages/raw/master/install | bash
详见：https://wiki.omv-extras.org/
如果以下命令访问有问题，可以用以下步骤：
#1.
apt-get update
#2
apt-get install dirmngr
#3.
apt --fix-broken install
#4.
apt-get --yes --no-install-recommends install dirmngr gnupg
#5.
wget http://omv-extras.org/openmediavault-omvextrasorg_latest_all5.deb
#6.
dpkg -i openmediavault-omvextrasorg_latest_all5.deb