To enable this feature, gentoo will have come auto completion/notify for command. But in gentoo, there are some tricky should be note.
1. install gentoo-bashcomp, it will also imstall bash_completion and mush more syntax file
# emerge gentoo-bashcomp
2. enable the syntax of gentoo
# eselect bashcomp enable --global gentoo
3. for other syntax, IMPORTANT: the base must be enable by default
# eselect bashcomp enable --global base ssh info man
After enabling base and ssh, you can use ssh<TAB><TAB> to get the listing you have connected. And the man and info are also useful when we want to search for partial command. Enjoy it 😀