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docs/CONVERTING_TO_HOMED: format text

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@ -8,11 +8,12 @@ SPDX-License-Identifier: LGPL-2.1-or-later
# Converting Existing Users to systemd-homed managed Users
Traditionally on most Linux distributions, regular (human) users are managed
via entries in `/etc/passwd`, `/etc/shadow`, `/etc/group` and
`/etc/gshadow`. With the advent of
via entries in `/etc/passwd`, `/etc/shadow`, `/etc/group` and `/etc/gshadow`.
With the advent of
[`systemd-homed`](https://www.freedesktop.org/software/systemd/man/systemd-homed.service.html)
it might be desirable to convert an existing, traditional user account to a
`systemd-homed` managed one. Below is a brief guide how to do that.
`systemd-homed` managed one.
Below is a brief guide how to do that.
Before continuing, please read up on these basic concepts:
@ -23,20 +24,20 @@ Before continuing, please read up on these basic concepts:
## Caveat
This is a manual process, and possibly a bit fragile. Hence, do this at your
own risk, read up beforehand, and make a backup first. You know what's at
stake: your own home directory, i.e. all your personal data.
This is a manual process, and possibly a bit fragile.
Hence, do this at your own risk, read up beforehand, and make a backup first.
You know what's at stake: your own home directory, i.e. all your personal data.
## Step-By-Step
Here's the step-by-step guide:
0. Preparations: make sure you run a distribution that has `systemd-homed`
enabled and properly set up, including the necessary PAM and NSS
configuration updates. Make sure you have enough disk space in `/home/` for
a (temporary) second copy of your home directory. Make sure to backup your
home directory. Make sure to log out of your user account fully. Then log in
as root on the console.
enabled and properly set up, including the necessary PAM and NSS configuration updates.
Make sure you have enough disk space in `/home/` for a (temporary) second copy of your home directory.
Make sure to backup your home directory.
Make sure to log out of your user account fully.
Then log in as root on the console.
1. Rename your existing home directory to something safe. Let's say your user
ID is `foobar`. Then do:
@ -45,92 +46,86 @@ Here's the step-by-step guide:
mv /home/foobar /home/foobar.saved
```
2. Have a look at your existing user record, as stored in `/etc/passwd` and
related files. We want to use the same data for the new record, hence it's good
looking at the old data. Use commands such as:
2. Have a look at your existing user record, as stored in `/etc/passwd` and related files.
We want to use the same data for the new record, hence it's good looking at the old data.
Use commands such as:
```
getent passwd foobar
getent shadow foobar
```
This will tell you the `/etc/passwd` and `/etc/shadow` entries for your
user. For details about the fields, see the respective man pages
This will tell you the `/etc/passwd` and `/etc/shadow` entries for your user.
For details about the fields, see the respective man pages
[passwd(5)](https://man7.org/linux/man-pages/man5/passwd.5.html) and
[shadow(5)](https://man7.org/linux/man-pages/man5/shadow.5.html).
The fourth field in the `getent passwd foobar` output tells you the GID of
your user's main group. Depending on your distribution it's a group private
to the user, or a group shared by most local, regular users. Let's say the
GID reported is 1000, let's then query its details:
The fourth field in the `getent passwd foobar` output tells you the GID of your user's main group.
Depending on your distribution it's a group private to the user, or a group shared by most local, regular users.
Let's say the GID reported is 1000, let's then query its details:
```
getent group 1000
```
This will tell you the name of that group. If the name is the same as your
user name your distribution apparently provided you with a private group for
your user. If it doesn't match (and is something like `users`) it apparently
didn't. Note that `systemd-homed` will always manage a private group for
each user under the same name, hence if your distribution is one of the
latter kind, then there's a (minor) mismatch in structure when converting.
This will tell you the name of that group.
If the name is the same as your user name your distribution apparently provided you with a private group for your user.
If it doesn't match (and is something like `users`) it apparently didn't.
Note that `systemd-homed` will always manage a private group for each user under the same name,
hence if your distribution is one of the latter kind, then there's a (minor) mismatch in structure when converting.
Save the information reported by these three commands somewhere, for later
reference.
Save the information reported by these three commands somewhere, for later reference.
3. Now edit your `/etc/passwd` file and remove your existing record
(i.e. delete a single line, the one of your user's account, leaving all
other lines unmodified). Similar for `/etc/shadow`, `/etc/group` (in case
you have a private group for your user) and `/etc/gshadow`. Most
distributions provide you with a tool for that, that adds safe
(i.e. delete a single line, the one of your user's account, leaving all other lines unmodified).
Similar for `/etc/shadow`, `/etc/group` (in case you have a private group for your user) and `/etc/gshadow`.
Most distributions provide you with a tool for that, that adds safe
synchronization for these changes: `vipw`, `vipw -s`, `vigr` and `vigr -s`.
4. At this point the old user account vanished, while the home directory still
exists safely under the `/home/foobar.saved` name. Let's now create a new
account with `systemd-homed`, using the same username and UID as before:
exists safely under the `/home/foobar.saved` name.
Let's now create a new account with `systemd-homed`, using the same username and UID as before:
```
homectl create foobar --uid=$UID --real-name=$GECOS
```
```sh
homectl create foobar --uid=$UID --real-name=$GECOS
```
In this command line, replace `$UID` by the UID you previously used,
i.e. the third field of the `getent passwd foobar` output above. Similar,
replace `$GECOS` by the GECOS field of your old account, i.e the fifth field
of the old output. If your distribution traditionally does not assign a
private group to regular user groups, then consider adding `--member-of=`
with the group name to get a modicum of compatibility with the status quo
ante: this way your new user account will still not have the old primary
i.e. the third field of the `getent passwd foobar` output above.
Similar, replace `$GECOS` by the GECOS field of your old account, i.e the fifth field of the old output.
If your distribution traditionally does not assign a private group to regular user groups,
then consider adding `--member-of=` with the group name to get a modicum of compatibility with the status quo ante:
this way your new user account will still not have the old primary
group as new primary group, but will have it as auxiliary group.
Consider reading through the
[homectl(1)](https://www.freedesktop.org/software/systemd/man/homectl.html)
manual page at this point, maybe there are a couple of other settings you
want to set for your new account. In particular, look at `--storage=` and
`--disk-size=`, in order to change how your home directory shall be stored
manual page at this point, maybe there are a couple of other settings you want to set for your new account.
In particular, look at `--storage=` and `--disk-size=`, in order to change how your home directory shall be stored
(the default `luks` storage is recommended).
5. Your new user account exists now, but it has an empty home directory. Let's
now migrate your old home directory into it. For that let's mount the new
home directory temporarily and copy the data in.
1. Your new user account exists now, but it has an empty home directory.
Let's now migrate your old home directory into it.
For that let's mount the new home directory temporarily and copy the data in.
```
homectl with foobar -- rsync -aHANUXv --remove-source-files /home/foobar.saved/ .
```
This mounts the home directory of the user, and then runs the specified
`rsync` command which copies the contents of the old home directory into the
new. The new home directory is the working directory of the invoked `rsync`
process. We are invoking this command as root, hence the `rsync` runs as
root too. When the `rsync` command completes the home directory is
automatically unmounted again. Since we used `--remove-source-files` all files
copied are removed from the old home directory as the copy progresses. After
the command completes the old home directory should be empty. Let's remove
it hence:
`rsync` command which copies the contents of the old home directory into the new.
The new home directory is the working directory of the invoked `rsync` process.
We are invoking this command as root, hence the `rsync` runs as root too.
When the `rsync` command completes the home directory is automatically unmounted again.
Since we used `--remove-source-files` all files copied are removed from the old home directory as the copy progresses.
After the command completes the old home directory should be empty.
Let's remove it hence:
```
rmdir /home/foobar.saved
```
And that's it, we are done already. You can log out now and should be able to
log in under your user account as usual, but now with `systemd-homed` managing
your home directory.
And that's it, we are done already.
You can log out now and should be able to log in under your user account as usual,
but now with `systemd-homed` managing your home directory.