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title: Mounting music dir before MPD
tags: systemd, mpd, config
date: 2013-11-24 14:03
format: md
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Systemd allows you to specify a program to run before running the main
daemon (or program) with `ExecStartPre`. This can, for instance, be
used to run a mount command before starting `mpd`. By adding under the
`[Service]` heading:

    ExecStartPre=/usr/bin/mount /mnt/music

Now I have already setup my `fstab` to know what to mount on
`/mnt/music`, but of course that shouldn't be necessary. According to
the `systemd.service(5)` man page it uses the same syntax as
`ExecStart`, which tells us that one must use absolute file names
since no shell is used to start them.

This also has the effect of stopping the `ExecStart` part from the
`.service` from being executed if the `ExecStartPre` doesn't finish
successfully. Which works out great in my case as I don't want to
start `mpd` if my music directory didn't mount. If you want to ignore
the exit status of (one of) the `ExecStartPre` commands you can prefix
it with a `-`, for example:

    ExecStartPre=-/usr/bin/mount /mnt/music

Which would continue running the `ExecStart` even if mounting failed.

Also know that there can be multiple `ExecStartPre` options and they
will be executed serially, so for example:

    ExecStartPre=/usr/bin/mount /mnt/music
    ExecStartPre=-/usr/bin/mount /mnt/music2

This would fail if `/mnt/music` doesn't mount, but would continue just
fine if `/mnt/music` did and `/mnt/music2` didn't.