/usr/bin/debbie was fine, as far as quoting goes.
Modded it to pass environment variables rightly (su was stomping them), but still needs sudoers tweak: Code: Defaults env_keep+=GTK_MODULES user ALL = NOPASSWD: /sbin/debian Note that the second line suffices, for our purposes, instead of the ALL = NOPASSWD: ALL that we've been using. Your call which to go with; by letting the user chroot to an arbitrary FS image, they already own the system if they want it. It's not any better security-wise, but might save someone somewhere from doing something stupid. The first line, though, lets us pass GTK_MODULES through, which we need.
Defaults env_keep+=GTK_MODULES user ALL = NOPASSWD: /sbin/debian