I'd like to mount /tmp without fstab entry using tmp.mount

However on Ubuntu 20.04 LTS, it doesn't seem to work.

user@user-x1:~$ systemctl status tmp.mount 
Unit tmp.mount could not be found.
user@user-x1:~$ sudo systemctl enable tmp.mount 
Failed to enable unit: Unit file tmp.mount does not exist.
user@user-x1:~$ sudo systemctl cat tmp.mount 
No files found for tmp.mount.
user@user-x1:~$ cat /usr/share/systemd/tmp.mount 
#  SPDX-License-Identifier: LGPL-2.1+
#  This file is part of systemd.
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

Description=Temporary Directory (/tmp)
Before=local-fs.target umount.target



What's happening? Why does systemd say unit could not be found even though bash auto tabbing fills up tmp.mount and what's the simplest way to enable this tmpfs without any config?

2 Answers 2


tmp.mount is not enabled by default. Just copy and enable it

sudo cp -v /usr/share/systemd/tmp.mount /etc/systemd/system/ 
sudo systemctl enable tmp.mount
  • Thanks @ExploitFate!
    – x70766c
    Apr 28, 2020 at 9:56
  • 1
    Maybe symlink (ln -s) would be better than copy (cp). But it's just a detail :)
    – Messa
    Nov 8, 2021 at 11:29

Note that systemctl enable accept absolute paths to unit files. (See systemctl man page) So there's no need to copy it manually.

I have tested on Ubuntu 22.04:

$ sudo systemctl enable /usr/share/systemd/tmp.mount
Created symlink /etc/systemd/system/local-fs.target.wants/tmp.mount → /usr/share/systemd/tmp.mount.
Created symlink /etc/systemd/system/tmp.mount → /usr/share/systemd/tmp.mount.
  • Interesting. And will systemd deal with all the required configuration details, e.g. properly formatting the in-memory /tmp and so forth (or whatever the initialisation it requires)? All I see on Ubuntu 22.04 is that it is expected to eat up 50% of all available memory, which seems to me to be overkill... Sep 7, 2022 at 17:08
  • @GwynethLlewelyn "formatting" a tmpfs makes no sense, it's a virtual filesystem so the kernel just provides you with a clean one when asked. tmpfs allowing use of up to 50% of RAM is the default, but that doesn't mean that 50% of RAM is immediately marked as used when a tmpfs is mounted.
    – muru
    Jan 30 at 8:06

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .