Preserve /home during reinstall?

[acampbell]

Originally Posted by jggimi

There are four things I can think of that would remove all files from a filesystem.

1. Re-formatting with newfs(8).
2. Removing them with an accidental rm(1) -r.
3. An fsck(8) of a very damaged filesystem with either a "-y" option or answering "yes" to removing each and every file.
4. Accidentally running the ramdisk's install script rather than the update script. This would cause #1 to occur.

Thanks iggimi. I think 4 may be the answer. I also thought you could simply enter the shell without running update but I presume that's wrong.

[jggimi]

Yes you can enter the shell. When you boot the ramdisk kernel, you get the following prompt:

(I)nstall, (U)pgrade, (A)utoinstall or (S)hell?

As you can see it is one of your four choices.

[Reeshar]

Originally Posted by jggimi

To recover /home without loss during an install, you must be sure that:

1. There is no /home partition defined during the install.
2. That you capture the starting sector and size from the existing disklabel.
3. That the install does NOT assign any sectors from the area currently containing /home to any partition.
4. That after installation, you define the partition in the disklabel using the starting sector and length you recorded.
5. That you add the partition to your fstab(5).

As a test to see if it worked, I followed this rather tedious process to maintain the existing partition structure but save the home directory across installs. I don't know what you think of it!

Assuming the /home directory is the k partition on disk sd0 and you're logged in as root:

1. Install new OS but when disklabel runs select existing OBSD partition, choose e(dit) and then:

> n k
mount point (/home) > none
> w
> x

2. With the new OS installed, assuming you've recreated the users as before:

# cd /home
# rm -r *
(to remove any created home directories but keep the /home mount point)

# disklabel -E -F /etc/fstab sd0
> m k
(keep size etc)
mount point > /home
> w
> x

3. (And I don't know whether this was necessary but the cpg value was wrong for the k partition so I updated it):

# disklabel -e sd0

(this invokes vi. Just change the cpg value to the same as the others - and the same as it was before - and save)

4. #disklabel sd0
....to check everything is fine and then...

5. Reboot!

I've written this up from memory so hopefully I've not made any mistakes. It's based on a total lack of knowledge of how disklabel and the install process work!