Bash SSH host auto completion

By default the ssh command does not support auto completion for host names. However, it stores all hosts you have accessed in the ~/.ssh/known_hosts file. We can take this data and use it for an auto completion function.

Create the following file in your home folder (yes, I know, another secret file):

~/.ssh-completion.bash

_complete_ssh_hosts ()
{
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    comp_ssh_hosts=`cat ~/.ssh/known_hosts | \
                    cut -f 1 -d ' ' | \
                    sed -e s/,.*//g | \
                    grep -v ^# | \
                    uniq | \
                    grep -v "\[" ;
            cat ~/.ssh/config | \
                    grep "^Host " | \
                    awk '{print $2}'
            `
    COMPREPLY=( $(compgen -W "${comp_ssh_hosts}" -- $cur))
    return 0
}
complete -F _complete_ssh_hosts ssh

Then make it executable:

chmod +x ~/.ssh-completion.bash

And source the file in your bash profile.

test -f ~/.ssh-completion.bash && . $_

Restart bash and you should get auto completion for the ssh command.

Note: This will not work for Ubuntu as it hashes everything in the known_hosts file.