sshrc.txt

## Modified solution of: http://superuser.com/a/180149
## If it is not pointing at an active socket, make the link.
if test "$SSH_AUTH_SOCK" ; then
    real_sock=$(readlink ~/.ssh/ssh_auth_sock)
    if [ -z "$real_sock" -o ! -S "$real_sock" ]; then
        ln -sf $SSH_AUTH_SOCK ~/.ssh/ssh_auth_sock
    fi
fi

And in ~/.screenrc

## Save me from having to twiddle with the auth sock every time I reattach to a screen
setenv SSH_AUTH_SOCK $HOME/.ssh/ssh_auth_sock