Overriding exit to tmux detach

I was using mosh like this:
```bash
function mssh {
    echo "> mosh --no-init $1 -- tmux new-session -A -s main"
    mosh --no-init $1 -- tmux new-session -A -s main
}
```

But sometimes I would enter `exit` instead of `tmux detach` and I would lose the session I had on the remote!

So I found this code block that I inserted into my remote `~/.bashrc` that would help me. It's simple to read, if the session is not tmux, we exit, but if it is, check if it is desirable to preserve the session.

```bash
# also see https://medium.com/@toja/tip-using-mosh-with-scrollback-257a54a848b3
exit() {
  if [[ -z $TMUX ]]; then
    builtin exit
    return
  fi

  panes=$(tmux list-panes | wc -l)
  wins=$(tmux list-windows | wc -l)
  count=$(($panes + $wins - 1))
  if [ $count -eq 1 ]; then
    tmux detach
  else
    builtin exit
  fi
}
``` 

Note, pressing (CTRL+D) will still exit the session, if you want.

tags: code