Am 15.02.2014 21:13, schrieb Colin Watson: > On Sat, Feb 15, 2014 at 08:12:45PM +0100, Michael Biebl wrote: >> I noticed that the SysV init script runs >> update-binfmts --disable on stop >> >> The systemd service doesn't though. >> Is this difference in behaviour deliberate or should we >> also run disable on stop in the service file? >> >> This could be done via >> >> ExecStop=/usr/sbin/update-binfmts --disable > > It's an interesting question. If you look closely at the sysvinit > script, you'll see that it does define a stop action, but there's no > Default-Stop; that means you can stop it manually if you want to, but it > doesn't slow down shutdown by doing unnecessary work. > > Is there a way to achieve a similar effect with systemd? I haven't been > able to find one by looking through the manual pages.
Yeah, this is possible. binfmt-support.service uses DefaultDependencies=yes (the default value). Aside from a set of orderings and dependencies this also adds Conflicts=shutdown.target. See # systemctl -p Conflicts show binfmt-support.service This ensures, whenever the shutdown.target is activated, that unit is stopped. If you want to see which units will be stopped if you enter the shutdown target, run # systemctl -p ConflictedBy show shutdown.target By using DefaultDependencies=no, you have more fine-grained control over which dependencies and orderings are added to your service. Usually, that property should only be used for early boot services, though [1]. You also need to make sure to specify your dependencies/orderings explictly now. Untested: [Unit] Description=Enable support for additional executable binary formats Documentation=man:update-binfmts(8) DefaultDependencies=no After=local-fs.target proc-sys-fs-binfmt_misc.automount [Service] Type=oneshot RemainAfterExit=yes ExecStart=/usr/sbin/update-binfmts --enable ExecStop=/usr/sbin/update-binfmts --disable Restart=no [Install] WantedBy=multi-user.target > (The stop action is mostly a nicety, so if this isn't achieveable, I > think it would be better to omit ExecStop rather than slowing down > shutdown.) The combination of multi-user.target and DefaultDependencies=no is a bit odd and if it's worth adding that, I'll leave to your discretion. I've CCed the pkg-systemd-maintainers mailing list since I think this issue is interesting enough for a wider audience. Regards, Michael [1] man 5 systemd.unit -- Why is it that all of the instruments seeking intelligent life in the universe are pointed away from Earth?
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