Bash auto-complete (e.g. show options "now tomorrow never" when you press'tab' after typing "dothis")
complete -W "now tomorrow never" dothis
# ~$ dothis
# never now tomorrow
# press 'tab' again to auto-complete after typing 'n' or 't'
complete -W "now tomorrow never" dothis
# ~$ dothis
# never now tomorrow
# press 'tab' again to auto-complete after typing 'n' or 't'