Description of problem: usermod when used with -u option blindly tries to change the ownership of all files in home directory to a new uid. This is not a good idea if the home directory is set to '/'. Version-Release number of selected component (if applicable): shadow-utils-4.0.18.1-22.fc8 How reproducible: Always Steps to Reproduce: 1. usermod -d / someuser 2. usermod -u 1234 someuser Actual results: Broken system. Expected results: Error message or warning message and no change of ownership on files. Additional info: I've ran into this bug by an accident while tuning a server running Fedora 8. I was fixing uid of users for compliance to a new local policy, and tried to change the uid of the user 'pulse' which had default home directory '/' on fedora 8 installation. Fortunately hit Ctrl-C just in time.
This is not a bug, but I have suggested a small change in behaviour that could help. See upstream: http://lists.alioth.debian.org/pipermail/pkg-shadow-devel/2009-April/007065.html
Well, classification of such 'features' as bugs or features is a matter of philosophy. Anyway, I completely agree with your proposed change. I would also suggest to add some option like 'force chown_tree anyway'.