FYI, [cc'ing the yum list, because yum may want to make the permissions of certain files it creates be independent of root's umask ] When I do things as root, I have umask set to 077. That appears to have led yum to set the permissions on all files in /var/lib/yum/rpmdb-indexes/ to -rw-------. That in turn makes commands run by non-root like "yum info libvirt" fail, and it also makes libguestfs' build process fail like this: febootstrap: external python program failed, see earlier error messages The previous error it's referring to appears to be this: IOError: [Errno 13] Permission denied: '//var/lib/yum/rpmdb-indexes/version' I've just run this command (as root), chmod go+r /var/lib/yum/rpmdb-indexes/* the libguestfs build was finally able to complete. And "yum info ..." became usable again. This is on Fedora 15.