Comment by pmlnr | Hacker News Reader

Comment by pmlnr | Hacker News Reader

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Story from yesterday: I foolishly modified fstab, like I did for over a decade, to swap a mountpoint from a local drive to NFS. What happened: `mount -a` ran fine. No errors. Except... the mountpoint was empty, there was no match in `mount` output to the line.

After poking the internet:

    After altering fstab one should either run systemctl 
    daemon-reload (this makes systemd to reparse /etc/fstab 
    and pick up the changes) or reboot[^1].

So, the summary with systemd: it will break something for everyone sooner or later. It hopefully won't be something you can't fix, but it will make you very angry and in immediate need of a tea break.

BTW, this is not the first one for me, but certainly one of the most frustrating ones, and not because of the behaviour: because of the lack of error messages on stderr or at least in syslog. The messages in ~~syslog~~ journald were casual.

[^1]: https://unix.stackexchange.com/questions/169909/systemd-keep...

Actually it's been like that for a long time, and for a good reason.

/etc/fstab is parsed by systemd and converted int .mount unit files, so that they can be mounted when a) asked for it (auto/noauto) and b) as soon as possible.

think of the _netdev flag: it signals systemd that a mountpoint is network-based, and thus it will attempt to mount it only after the networking target (instead of waiting for it to timeout at boot time, fail , and possibly letting processes start reading and writing from/to an empty directory).

Running daemon-reload is generally system(d)-wide though: whenever systemd configuration is altered (think adding/removing/updating an unit file) you should let systemd know about that by running systemd daemon-reload (think of apachectl reload).

> and for a good reason

Yeah... there's always a "good reason" with systemd, isn't there?

Still doesn't account for the lack of error message.

It's kind of funny how systemd breaks often when old farts (like us) tinker with something in a way we shouldnt.

It's non-obvious, though. Change something in /etc/systemd you can expect to have to tell systemd about it. Outside of that directory, there's no indicator you should do so.

"Long time" is also relative. I've been updating /etc/fstab directly for over 25 years.

Why doesn't it reparse fstab before executing mount commands?

the mount command is not part of systemd

mount the command DOES read /etc/fstab I believe the discussion was a systemd mount unit

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