http://old.nabble.com/Reattaching-to-a-detached-screen-td21191445.html

re-screen.sh

if [[ "$TERM" != vt320 ]]; then
  if ! which screen|grep "no screen"; then
    if screen -ls|head -n3|tail -n2|cut -f2|cut -d. -f2-|grep -q
'^'main'$'; then
      exec screen -r main
    else
      exec screen -S main
    fi
  fi
fi 

reattach-screen.sh

## The naive "chsh -s /usr/bin/screen" breaks scp (and other things).
## Have sh start screen automatically "when appropriate".  That is,
## 1) not in a screen window (STY);
## 2) stdin is a tty;
## 3) screen is installed; and
## 4) terminal is capable of displaying screen.
## Replace "$STY" with "$STY$SSH_CLIENT$SSH_ORIGINAL_COMMAND" to avoid
## nesting screens when sshing (untested).
test -z "$STY" -a -t 0 &&
{ which screen && tput clear && tput cup && ! tput hc && ! tput os
} &>/dev/null &&              # ignore boring, expected error messages
{
    ## Set the window title to the host name.
    ## Note that using echo -e \e for ^[ is not portable.
    case "$TERM" in
        screen*) printf %bk%s%b%b \\033 "${HOSTNAME%%.*}" \\033 \\0134;;
    esac
    ## If new session, start agents.
    screen -ls | grep -qi 'No Sockets found' &&
    eval "$(twb-agents)"
    ## Start screen.
    exec screen -DRR
}

## If execution reaches this point, screen isn't the login shell.  In
## that case, if this is a bash shell, it's a good idea to do the
## bashisms in .bashrc.
test -n "$BASH" &&
test -f ~/.bashrc &&
. ~/.bashrc