命令如下：
sudo apt-get update
报错信息如下
>E: Problem executing scripts APT::Update::Post-Invoke-Success ‘if /usr/bin/test -w /var/cache/app-info -a -e /usr/bin/appstreamcli; then appstreamcli refresh > /dev/null; fi’
>E: Sub-process returned an error code
解决办法如下：
链接：https://bugs.launchpad.net/ubuntu/+source/appstream/+bug/1579712/comments/24
>cd /tmp && mkdir asfix
>cd asfix
>wget https://launchpad.net/ubuntu/+archive/primary/+files/appstream_0.9.4-1ubuntu1_amd64.deb
>wget https://launchpad.net/ubuntu/+archive/primary/+files/libappstream3_0.9.4-1ubuntu1_amd64.deb
>sudo dpkg -i *.deb
