A common /home partition for multiple Linux distributions

Ubuntus graphical installer does not automatically create a separate partition for /home. That's true. It is recommendable to do so though, and you can do it if you choose to manually partition. But even if you didn't, you can still fix it.

However, there are a few things to consider. First, make sure that all the distros can actually use the filesystem used on the home partition. It's usually not a problem, but better safe than sorry. Second, and this is more important; don't use the same home directory between distros unless you know what you're doing. The distros may have different versions of the installed software, meaning that their settings might not be identical. It should normally not be a problem since the applications should handle different versions properly, but not all do. It is perfectly fine to have a home directory with a different name than your username though, so that's not a problem.

If I'm reading correctly, you should have two partitions for Ubuntu (swap and root) and a few partitions for Debian. Then the first thing you do, is to mount Debians home directory in Ubuntu and make sure it's mounted at boot by adding it to /etc/fstab. There are loads of documentation on how to do this, so I won't go into it.

If you mount Debians home partition on /home, then it will hide Ubuntus /home directory, so mount it somewhere else first, in /mnt, for instance. Now you have to make some decisions. You can try to use the same home directory for all the distros if you want, or you can have a different home directory for each distro. You could for instance make a separate folder in /home for each distro like:

• /home/ubuntu/username
• /home/debian/username
• /home/other_distro/username

I'd say that's the safest solution. I am assuming your home directories are not encrypted. If they are, then that will complicate things although the main procedure would be similar. You should probably be logged out of your main account when you do this, so create a new user, make it admin and login as that user.

You have to configure all the current users on all your distros to use the new location for the home directory. You should also configure the distros to use those paths by default for new users you create.

If you've mounted the home partition on /mnt, you'd then create /home/ubuntu and /home/debian. You then copy /home/username to /mnt/ubuntu/username and move /mnt/username to /mnt/debian/username (for the Debian user).

You now have both Ubuntu and Debians user homes in the same partitions, but in different home directories. If you have configured both Debian and Ubuntu to mount that partition in /home at boot and changed the users to use the new paths for their homes, then everything should be fine. When you intend to install a new distro, you'd first create /home/distroname/ and install as usual, but use the home partition and configure it to use /home/distroname as default location for new user homes. If you do that, make sure not to format it, otherwise you'll loose the data from Debian and Ubuntu :)

If you want to reuse a single home directory, make sure you know what you're doing. You would need to have the same uid for the users across the distros. Otherwise the permissions would be messed up.

Good luck and take backups :)

This is a late answer, but might be useful for others trying to share info between distros.

As mentioned above, there are issues with applications with different versions sharing the same configuration files in /home/user/.

A simple solution that solves part of the problem, i.e. to share most of the data in the home folder, is to symlink folders like /home/user/Documents. My home folder looks like this:

drwxr-xr-x  3 mike mike 4096 May  2 11:48 Desktop/
drwxr-xr-x  2 mike mike 4096 May  1 21:18 Downloads/
lrwxrwxrwx  1 mike mike   34 Apr 27 12:36 Documents -> /mnt/home/mike/Documents/
lrwxrwxrwx  1 mike mike   33 Apr 27 12:40 Pictures -> /mnt/home/mike/Pictures/
lrwxrwxrwx  1 mike mike   32 Apr 27 12:38 Public -> /mnt/home/mike/Public/
lrwxrwxrwx  1 mike mike   31 Apr 27 12:39 Videos -> /mnt/home/mike/Videos/
lrwxrwxrwx  1 mike mike   34 Apr 27 12:40 workspace -> /mnt/home/mike/workspace/

As can be seen above the Desktop and the Download folders are on the local home partition while Documents, Pictures etc. are linked to a shared partition.

Here is how to setup a symlink (in this example for the Documents folder):

$ cd ~
$ mkdir old-folders
$ mv Documents old-folders/
$ ln -s /mnt/home/mike/Documents/ Documents

The above moves the current Documents folder to old-folders and set up a symbolic link to a shared Documents folder. I've used this scheme for a long time and had no issues so far.

You might find issues with the trash can, if so, check this posting: How do I use gnome trash for files in different partition?

As it is technically possible to share the /home directory from different distributions (see this answer) it is not a good idea to do so.

Application's settings may have different formats from different program versions. If anything is incompatible or goes out of sync by this we would be entirely lost to find the cause. It is not even recommended to do so within different versions of the same distribution (see e.g. here).

Therefore it is recommended to share personal data files from subdirectories of the user's home only (e.g. by creating symlinks to a directory of your choice):