我正在尝试该命令systemctl enable multi-user.target，但得到以下信息：
The unit files have no installation config (WantedBy=, RequiredBy=, Also=,
Alias= settings in the [Install] section, and DefaultInstance= for template
units). This means they are not meant to be enabled using systemctl.
Possible reasons for having this kind of units are:
• A unit may be statically enabled by being symlinked from another unit's
.wants/ or .requires/ directory.
• A unit's purpose may be to act as a helper for some other unit which has
a requirement dependency on it.
• A unit may be started when needed via activation (socket, path, timer,
D-Bus, udev, scripted systemctl call, ...).
• In case of template units, the unit is meant to be enabled with some
instance name specified.
同样的事情发生在systemctl enable graphical.target
尝试同时使用systemctl disable两者没有效果
注意：我可以使用systemctl isolate或systemctl set-default然后重新启动来切换到任何启动目标。但我只是想知道为什么systemctl enable/disable不适用于mult-user.target和graphical.target。