2.10) How do I tell inside .cshrc if I'm a login shell?

      When people ask this, they usually mean either

        How can I tell if it's an interactive shell?  or
        How can I tell if it's a top-level shell?

      You could perhaps determine if your shell truly is a login shell
      (i.e. is going to source ".login" after it is done with ".cshrc")
      by fooling around with "ps" and "$$".  Login shells generally
      have names that begin with a '-'.  If you're really interested in
      the other two questions, here's one way you can organize your
      .cshrc to find out.

        if (! $?CSHLEVEL) then
                #
                # This is a "top-level" shell,
                # perhaps a login shell, perhaps a shell started up by
                # 'rsh machine some-command'
                # This is where we should set PATH and anything else we
                # want to apply to every one of our shells.
                #
                setenv      CSHLEVEL        0
                set home = ~username        # just to be sure
                source ~/.env               # environment stuff we always want
        else
                #
                # This shell is a child of one of our other shells so
                # we don't need to set all the environment variables again.
                #
                set tmp = $CSHLEVEL
                @ tmp++
                setenv      CSHLEVEL        $tmp
        endif

        # Exit from .cshrc if not interactive, e.g. under rsh
        if (! $?prompt) exit

        # Here we could set the prompt or aliases that would be useful
        # for interactive shells only.

        source ~/.aliases