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In order to support offline updates to /usr, we need to be able to run certain tasks on next boot-up to bring /etc and /var in line with the updated /usr. Hence, let's devise a mechanism how we can detect whether /etc or /var are not up-to-date with /usr anymore: we keep "touch files" in /etc/.updated and /var/.updated that are mtime-compared with /usr. This means: Whenever the vendor OS tree in /usr is updated, and any services that shall be executed at next boot shall be triggered, it is sufficient to update the mtime of /usr itself. At next boot, if /etc/.updated and/or /var/.updated is older than than /usr (or missing), we know we have to run the update tools once. After that is completed we need to update the mtime of these files to the one of /usr, to keep track that we made the necessary updates, and won't repeat them on next reboot. A subsequent commit adds a new ConditionNeedsUpdate= condition that allows checking on boot whether /etc or /var are outdated and need updating. This is an early step to allow booting up with an empty /etc, with automatic rebuilding of the necessary cache files or user databases therein, as well as supporting later updates of /usr that then propagate to /etc and /var again.
22 lines
697 B
SYSTEMD
22 lines
697 B
SYSTEMD
# This file is part of systemd.
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#
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# systemd is free software; you can redistribute it and/or modify it
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# under the terms of the GNU Lesser General Public License as published by
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# the Free Software Foundation; either version 2.1 of the License, or
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# (at your option) any later version.
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[Unit]
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Description=Update is Completed
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Documentation=man:sysusers.d(5) man:systemd-sysusers(8)
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DefaultDependencies=no
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Conflicts=shutdown.target
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After=systemd-readahead-collect.service systemd-readahead-replay.service local-fs.target
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Before=sysinit.target shutdown.target
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RefuseManualStart=yes
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RefuseManualStop=yes
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[Service]
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Type=oneshot
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RemainAfterExit=yes
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ExecStart=@rootlibexecdir@/systemd-update-done
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