Symptom: when you try to tab complete a command, you see a message like this:
vi /et-sh: <( compgen -d -- '/et' ): No such file or directory
Cause: You're using sh, not bash, so even if tab completion is enabled on ~/.bashrc, it won't be available to you.
Solution: change the default shell for the current user from sh to bash with
chsh -s /bin/bash