Bash completion for ssh. Tested with Mac OS X 10.9

gistfile1.sh

# Add bash completion for ssh: it tries to complete the host to which you
# want to connect from the list of the ones contained in ~/.ssh/known_hosts
__ssh_known_hosts() {
    if [[ -f ~/.ssh/known_hosts ]]; then
        cut -d " " -f1 ~/.ssh/known_hosts | cut -d "," -f1 | grep -v "[\[\|]" | uniq | sort
    fi
}
_ssh() {
    local cur known_hosts
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    known_hosts="$(__ssh_known_hosts)"
    if [[ ! ${cur} == -* ]] ; then
        if [[ ${cur} == *@* ]] ; then
            COMPREPLY=( $(compgen -W "${known_hosts}" -P @ -- ${cur/*@/}) )
        else
            COMPREPLY=( $(compgen -W "${known_hosts}" -- ${cur}) )
        fi
    fi
    return 0
}
complete -o bashdefault -o default -o nospace -F _ssh ssh 2>/dev/null \
    || complete -o default -o nospace -F _ssh ssh