Why does iterm2 close new sessions immediately

Not sure why it didn't work with Login shell selected, but I changed it to ⌘ command and invoked bash -l or /bin/bash -l to make it work the same way. Hope this helps anyone else who has the same problem!

You could add something like this to the startup script of your default shell (mine is zsh, most people use bash, I guess, so you may have to tweak.)

Here's my bit of screen jiggery-pokery (in my .zshrc)

# Autoload screen if we aren't in it.  (Thanks Fjord!)
if [[ $STY = '' ]] then screen -xRR; fi

I got this from somewhere on the interwebs (I don't recall where, and I don't know who Fjord is, but good on him.

With this you can close your iTerm window, and it will resume where you left off when you reopen it. I highly recommend reading the screen man page also.