How do you access the contents of a previous mount after switching to a different the partition?

Question

I installed an additional Linux installation into a separate partition set the /home directory into that partition as well and afterwards I modified /etc/fstab to point to the old partition.

How can I access the contents of the initial /home directory?

# initial configuration
UUID=001  /disks/disk1part1  ext2  auto,users,rw,exec,relatime           0    0   
UUID=002  /                  ext4  defaults,relatime,errors=remount-ro   0    1   
UUID=003  /disks/disk26      ext4  auto,users,rw,exec,relatime           0    0   
UUID=004  none               swap  sw                                    0    0   

# changed configuration
UUID=001  /disks/disk1part1  ext2  auto,users,rw,exec,relatime           0    0
UUID=002  /                  ext4  defaults,relatime,errors=remount-ro   0    1
UUID=003  /home              ext4  auto,users,rw,exec,relatime           0    0
UUID=004  none               swap  sw                                    0    0

The initial system had no /home in /etc/fstab because it was under the root, and the second configuration added changed /home to /disks/disks26.

score 2 · Accepted Answer · answered Oct 02 '15 at 05:07

2

After a mount --bind / /mnt you can access the /home directory of your root partition as /mnt/home, even if /home is already mounted over.

answered Oct 02 '15 at 05:07

Ferenc Wágner

5,096

Does that affect other directories already mounted under /mnt? Can another name be used besides /mnt? – vfclists Oct 02 '15 at 09:48
If you mount something over /mnt, that will shadow all its previous content. I used /mnt because that's what routinely used for temporary mounts. You can use any other existing directory. – Ferenc Wágner Oct 02 '15 at 11:42
What does the --bind signify? Is there a special command to unmount it? – vfclists Oct 04 '15 at 01:41
A bind mount, see man mount. You can simply umount it as any other mount if it's not in use. – Ferenc Wágner Oct 04 '15 at 07:22
@vfclists http://unix.stackexchange.com/questions/198590/what-is-a-bind-mount – Gilles 'SO- stop being evil' Oct 04 '15 at 22:14

score 1 · Answer 2 · answered Oct 01 '15 at 13:30

1

A mere two edit (and two reboot).

comment line with /home; like

## UUID=003  /home              ext4  auto,users,rw,exec,relatime           0    0

reboot, log
```
cd /
mv /home /home.old
mkdir /home
```
edit /etc/fstab, uncomment.

What happened ?

As you guess new /home was mount over old /home, there is no way, save umounting to see old /home.

If you could umount /home, there is no need to reboot on above commands.

answered Oct 01 '15 at 13:30

Archemar

31,554

Isn't it possible to access via another means without changing the fstab and rebooting and renaming it? I am thinking along the lines of perhaps finding the inode and renaming it. Does changing the /home /etc/fstab make the /home inaccessible completely? It has to be there somewhere. – vfclists Oct 01 '15 at 13:36

How do you access the contents of a previous mount after switching to a different the partition?

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