ssh.md

### SSH config file

It is quite useful to have a `.ssh/config` file, which may look like:

```
Host $HOSTALIAS
        Hostname $HOST
        User $USER
        # from the outside we have to go through geniux
        ProxyJump geniux.molgen.mpg.de
        ForwardX11 yes
        # for jupyter
        LocalForward $PORT $HOST:$PORT

```
where you have to substitute the `$X` expressions
```
$HOST with your preferred compute server, e.g. nyancat
$HOSTALIAS with a short name for $HOST, e.g. ny
$USER with your user name
$PORT with the port number used for jupyter, otherwise comment this line
```


For more advanced options check out: `man ssh_config`



### tab-completion of hostnames

On the linux cluster the first 3 letters of most hostnames are unique. Therefore tab-completion works nicely after 3 letters only.
Put this code block in your `.bashrc`:


```
HOST_NAMES=( $( cut -f1 -d' ' ~/.ssh/known_hosts |\
                   tr ',' '\n' |\
                  sort -u |\
                 grep -e '[[:alpha:]]')
                $( awk '{print $1}' /etc/hostconfig |\
                   grep -v "^#" |\
                  grep -v "^$" |\
                 sort -u ) )
complete -o default -W "${HOST_NAMES[*]}" ssh
```