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Short version:

in /etc/fstab on an Ubuntu 18.04 system, what are the typical options used when mounting a partition as /home? Just "defaults 0 2", or something else?


Longer version:

I screwed up my /etc/fstab today, but managed to get it back. Something I was messing with basically deleted the /home entry in fstab, but I wasn't aware that it had done that, and the system kept working normally. When I went to reboot the system (for other reasons), the system was hosed and would not even let me log in (not even on the Ctrl+Alt+F3 console). I eventually zero'd in on the fstab problem, recreated the missing line, and I'm now posting from that system.

But I just put in a generic line, with options="defaults", dump=0 and pass=2. I suspect that dump and pass are fine as is, but I bet the options should be some besides the defaults. Can someone look at a vanilla 18.04 system and tell me what the options are for the /home mount? auto_da_alloc?

I did search this forum before posting. There's a thread from 2011 that says just defaults is fine, but that's 8 years old ...


Even longer version with background on the screwup:

I upgraded to 18.04 week ago. I kept my /home partition, copied to a new drive, and installed the OS around that. It had worked great for a week now.

Today I was working on setting up a backup process, and was fiddling around with mounting other drives, including an external drive. The external drive was an existing HDD that I was putting into a brand new SATA3/USB enclosure, so my first step was to just make sure that the new enclosure worked.

The new enclosure/drive showed up in Ubuntu's Disks utility, and I could see the old partitions. I mounted one of the partitions to confirm that worked, and ran a df (or something like that) to confirm it.

That's when I noticed that it had mounted the new partition at /home, apparently replacing the regular /home. Uh oh, the mount operation had followed the label of the partition (and yes I now understand why). A quick look at /home confirm that it was seeing the data on the old drive there. Yikes! I immediately unmounted it, and IT WENT BACK TO THE CORRECT HOME PARTITION. The correct files showed up at /home again. Whew, OK, don't do that again!

The system was working normally again, but what I didn't know was that in doing this, the Disks util had messed up the fstab file. The original /home entry was gone, and now the UUID of the correct partition was associated with another mount point (more detail that I'll skip here). The next time I rebooted, blammo, no /home.

After an hour of googling and thinking about what I had just been doing before it broke, I figured it out and restored it with a generic line in fstab.

Thanks for reading :)

  • If system not rebooted use /proc/mounts file to recreate fstab entries. – karthik Feb 11 at 6:16
  • karthik, I'm having trouble parsing what you said. I did some searching: google.com/search?q=%2Fproc%2Fmounts+fstab ... and reading and still don't understand. Does your comment relate to my question about the options, or are you pointing out how the OS still had /home mounted? – Chris C. Feb 12 at 23:45
  • This method is explained in this link it.toolbox.com/question/… – karthik Feb 13 at 3:52
  • Aha, thank you. And now your original comment makes perfect sense :) – Chris C. Feb 14 at 14:12
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Get UUID of partitions with sudo blkid
For GPT partitioned disks use sudo sgdisk
More information about UUID at Ubuntu Documentation : Using UUID

The 'builtin' /home line in fstab for an ext4 home partition:

# <file system> <mount point> <type> <options> <dump> <pass>
# /home
UUID=<a-string> /home ext4 defaults 0 2
  • Thanks for the UUID info, I got that. Is that example from an 18.04 install? So just "defaults 0 2" is what Ubuntu has been using for the /home mount on 18.04 installs? – Chris C. Feb 11 at 16:49
  • @Chris C. Yes, the line is as the default one created by Ubuntu install process – cmak.fr Aug 9 at 10:59
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OK, it sounds like there are no special settings for the /home mount in 18.04 systems -- just use "defaults 0 2" like I said in my original post.

Thanks cmak.fr and karthik!

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