the script I use to restore my ssh-agent settings to running screen sessions

agentscreen

#!/bin/bash

if [ "$TERM" != "screen" ]; then
    # if the auth socket variable is empty, don't do anything
    if [ ! -z "$SSH_AUTH_SOCK" ]; then
        # include USER to protect against shared HOME directories (rare)
        NEWSOCK=$HOME/.agent-sshscreen-$USER.sock
        if [ "$SSH_AUTH_SOCK" != "$NEWSOCK" ]; then
            # test if the auth sock we have is actually working
            # don't link to a dead socket
            if ssh-add -l > /dev/null 2>&1; then
                /bin/ln -sf $SSH_AUTH_SOCK $NEWSOCK
                export SSH_AUTH_SOCK=$NEWSOCK
            fi
        fi
    fi
    exec /usr/bin/screen "$@"
else
    echo "can't start up screen inside screen"
fi