if (-e !"/$home/.ssh/id_dsa.pub")

##</code><code>##

unless (-e "/$home/.ssh/id_dsa.pub")

##</code><code>##

if (-e !"/$home/.ssh/id_dsa.pub")
{
    `ssh-keygen -t dsa`
};

##</code><code>##

`ssh-keygen -t dsa` unless (-e "/$home/.ssh/id_dsa.pub");