Persistent SSH_AUTH_SOCK for using with screen/tmux

gistfile1.sh

# put this to your $HOME/.bashrc
# so you can safely use screen or tmux while preserving ssh-agent forwarding features
# of your ssh sessions
test "${SSH_AUTH_SOCK:-}" && test $SSH_AUTH_SOCK != $HOME/.ssh_auth_sock && {
        test -L $HOME/.ssh_auth_sock && \
                test "$(readlink $HOME/.ssh_auth_sock)" = $SSH_AUTH_SOCK || \
                ln -sf $SSH_AUTH_SOCK $HOME/.ssh_auth_sock
        export SSH_AUTH_SOCK=$HOME/.ssh_auth_sock
}