Greg Wooledge <[email protected]> writes: > By default, Debian installs the bash-completion package, which contains > programmable completions for a whole bunch of commands. This is > enabled by dotting in a file from ~/.bashrc (the code to do this is > at the end of /etc/skel/.bashrc, which becomes the default user ~/.bashrc > file if you add users with "adduser"). >
Reading this has solved something which has puzzled me for some time. My .bashrc is a leftover from when I was running Opensuse, and so bash completion has never quite worked properly on the su command. Now I have copied /etc/skel/.bashrc and it is working!

