0

I use Ubuntu 18.04 on an embedded system. By default it has tmpfs mounted on /dev/shm with 3.8G (~half RAM size) and some mount options.

I'm trying to change the /dev/shm size and mount options via the /etc/fstab. If I remount it, it works until next reboot, getting default values afterwards.

  1. I read that systemd can be used to configure this filesystem but they still recommend using the fstab file: Systemd backed tmpfs | How to specify /tmp size manually

  2. I read that some people changed the /etc/fstab entry from /dev/shm to /run/shm, but after doing so I had both filesystems mounted, not linked to each other: https://answers.launchpad.net/ubuntu/+question/232487

  3. I read that on redhat distributions , the /dev/shm is being mounted via boot from rc scripts but grep -r '/dev/shm' /etc/rc*/* returned nothing useful.

So how can I assure the /dev/shm mount options in /etc/fstab will take effect after reboot?

Improve this question
2
  • Does your embedded system have systemd-remount-fs.service? Commented May 23, 2023 at 6:00
  • I tried "systemctl mask dev-shm.mount" and "systemctl mask run-shm.mount" but still the changes in /etc/fstab regarding /dev/shm didn't apply (tried to reboot the system) Commented May 23, 2023 at 6:17

1 Answer 1

Reset to default
1

Originally I performed the following actions:

  1. Created some new partitions with ext4 filesystems.
  2. Mounted these new filesystems (on /var , /var/log , /home , and more..) and added suitable entries in /etc/fstab.
  3. Added new entries for tmpfs on /tmp and /dev/shm in /etc/fstab

When I perform step 3 before the others I get the desired results - the /dev/shm mount options remained changed even after reboot.

I don't know the exact reason but maybe the precedence of the /dev/shm entry upon the others in /etc/fstab has something to do with that.

Improve this answer

You must log in to answer this question.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.