Ubuntu 16.04出现：Problem executing scripts APT::Update::Post-Invoke-Success 'if /usr/bin/test -w /var/

错误：

Reading package lists... DoneE: 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

在运行sudo apt-get update时出现如上信息，解决方法如下：

sudo pkill -KILL appstreamcli

wget -P /tmp https://launchpad.net/ubuntu/+archive/primary/+files/appstream_0.9.4-1ubuntu1_amd64.deb https://launchpad.net/ubuntu/+archive/primary/+files/libappstream3_0.9.4-1ubuntu1_amd64.deb

sudo dpkg -i /tmp/appstream_0.9.4-1ubuntu1_amd64.deb /tmp/libappstream3_0.9.4-1ubuntu1_amd64.deb

执行完上述命令之后再次运行sudo apt-get update就不会再出现上面的错误。