我已经卸载memcached：
» sudo apt-get remove memcached
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
ieee-data python-netaddr python-selinux
Use 'sudo apt autoremove' to remove them.
The following packages will be REMOVED:
memcached
0 upgraded, 0 newly installed, 1 to remove and 9 not upgraded.
After this operation, 246 kB disk space will be freed.
Do you want to continue? [Y/n] y
(Reading database ... 377925 files and directories currently installed.)
Removing memcached (1.4.25-2ubuntu1.3) ...
Processing triggers for man-db (2.7.5-1) ...
但服务仍然列出：
» sudo service --status-all 2> /dev/null | grep memcached
[ - ] memcached
为什么？我该怎么做才能清理服务列表？
这是我的系统：
» lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.4 LTS
Release: 16.04
Codename: xenial