16.10.2017 18:15, 林自均 пишет: > Hi folks, > > I am reading systemd documents, and I find passive target units a little > bit confusing. > > Take "network.target" for example: > > "systemd-networkd.service" specifies "Wants=network.target" and > "Before=network.target". That effectively makes starting > "systemd-networkd.service" brings up both "systemd-networkd.service" and > "network.target", and make sure that "network.target" is active after > "systemd-networkd.service" being active. It also implies that the shutdown > order is correct: "network.target" will be stopped before > "systemd-networkd.service". Everything is fine. > > What if we use an active target unit to achieve all this? Can we specify a > "WantedBy=network.target" in "systemd-network.target"? So that we can > enable "systemd-network.service" (which makes a symbolic link in the > "network.target.wants" directory) and start "network.target" to pull in > "systemd-networkd.service". That also makes sure "network.target" is active > after "systemd-networkd.service" because of the target unit default > dependencies. And shutdown order will be correct too. > > The only difference I can tell is the units to start. With a passive > "network.target", we start "systemd-networkd.service". With an active > "network.target", we start "network.target". > > Is there any benefits of passive target units over active target units? >
I think it's historical artefact from the very early days when systemd had to rely on initscripts. initscript implementing networking did provide $network a.k.a network.target, but of course did not hook itself into native systemd units. As long as you are sure to use native units only there is no practical difference. _______________________________________________ systemd-devel mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/systemd-devel
