/etc/default/tmpfs, tmpfs for /tmp etc. Howto in systemd?

[Martin Pitt]

Hello U.Mutlu,

U.Mutlu [2019-03-30 20:34 +0100]:
> in /etc/default/tmpfs one can set /tmp to a tmpfs and give it a size from
> the avail RAM.

This was supported as an one-time migration from SysV init to systemd:

systemd (220-6) unstable; urgency=medium

  [...]
  * Stop installing tmp.mount by default; there are still situations where it
    becomes active through dependencies from other units, which is surprising,
    hides existing data in /tmp during runtime, and it isn't safe to have a
    tmpfs /tmp on every install scenario. (Closes: #783509)
    - d/rules: Ship tmp.mount in /usr/share/systemd/ instead of
      /lib/systemd/systemd.
    - systemd.postinst: When tmp.mount already was enabled, install tmp.mount
      into /etc and keep it enabled.
    - systemd.postinst: When enabling tmp.mount because of RAMTMP=yes, copy it
      from /usr/share.
    - Drop Don-t-mount-tmp-as-tmpfs-by-default.patch and
      PrivateTmp-shouldn-t-require-tmpfs.patch, not necessary any more.

 -- Martin Pitt <mpitt at debian.org>  Thu, 11 Jun 2015 09:25:49 +0200

But it's not a permanent setting -- /etc/default is SysV specific for the most
part, and it really doesn't fit into sytemd's architecture (which put an end to
these completely ad-hoc config file stuff).

You are free to enable tmp.mount yourself, but indeed (as you did) the most
straightforward way is to simply enable it in fstab.

Martin