Sometimes it’s useful to test stuff with an empty home filesystem. For example, if you want to test installing/setting up something as a new user without an existing configuration. Normally, you might just make a new user on the machine you’re using, but we obviously can’t do that, so the next best thing is to just clean the home filesystem.

To do this, we’ll use namespaces(7) to let us mount arbitrary filesystems without affecting the filesystem for all of the other users/processes on the machine.

To easily manipulate namespaces, we can use bwrap(1). I make a shell function for this so I don’t have to remember the command:

cleanroom() {
        bwrap --ro-bind / / --dev /dev --proc /proc --tmpfs $(realpath $HOME) /bin/zsh
}