Select the THREE true statements about where systemd unit files live and how changes to them take effect.
LPIC-1 Exam 101-500, objective 101. System architecture hard
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The options
Choose 3.
Correct /usr/lib/systemd/system holds the unit files installed by packages.
True. That directory is owned by the package manager, which is why local edits there are overwritten at the next upgrade.
Correct A unit file in /etc/systemd/system takes precedence over one of the same name in /usr/lib/systemd/system.
True. The administrator's directory is searched first, so a same-named file there replaces the vendor's copy entirely.
Correct A drop-in file in /etc/systemd/system/<unit>.d/ overrides selected settings without replacing the whole unit file.
True, and it is the preferred way to customise a packaged unit, since the rest of the vendor file continues to be maintained by the package. `systemctl edit <unit>` creates such a file.
Not correct Unit files under /run/systemd/system are ignored unless a configuration option enables that directory.
False. /run/systemd/system holds runtime units, is always searched, and ranks between /etc and /usr. Being on a tmpfs, its contents are discarded at reboot.
Not correct An edited unit file takes effect on the next systemctl start of that unit, with no further step.
False, and a common cause of confusion. The manager works from an in-memory copy of the configuration, so `systemctl daemon-reload` is required before the change is used.
Why
systemd searches for a unit by name across several directories in a fixed order of precedence: /etc/systemd/system first, then /run/systemd/system, then /usr/lib/systemd/system, and the first file found wins outright. Drop-in directories are the exception to winner-takes-all, because their fragments are merged onto whichever unit file won. The rule of thumb is to leave the vendor directory alone, express local policy in /etc, and follow every change with daemon-reload so the manager rereads what is on disk.
Where this comes from
- Cited
- manual page systemd.unit(5)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 101 and space the ones you get wrong.
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