Autocomplete remote machine names

.bashrc

complete -o default -o nospace -W "$(/usr/bin/env ruby -ne 'puts $_.split(/[,\s]+/)[1..-1].reject{|host| host.match(/\*|\?/)} if $_.match(/^\s*Host\s+/);' < $HOME/.ssh/config)" scp sftp ssh
_complete_hosts () {
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    host_list=`{
        for c in /etc/ssh_config /etc/ssh/ssh_config ~/.ssh/config
        do [ -r $c ] && sed -n -e 's/^Host[[:space:]]//p' -e 's/^[[:space:]]*HostName[[:space:]]//p' $c
        done
        for k in /etc/ssh_known_hosts /etc/ssh/ssh_known_hosts ~/.ssh/known_hosts
        do [ -r $k ] && egrep -v '^[#\[]' $k|cut -f 1 -d ' '|sed -e 's/[,:].*//g'
        done
        sed -n -e 's/^[0-9][0-9\.]*//p' /etc/hosts; }|tr ' ' '\n'|grep -v '*'`
    COMPREPLY=( $(compgen -W "${host_list}" -- $cur))
    return 0
}
complete -F _complete_hosts host
complete -F _complete_hosts ssh
complete -F _complete_hosts scp