http://www.fmi.uni-passau.de/archive/doc/unix/unixhelp/Unixhelp/basics_basic2.2.2.html (Einblicke ins Internet, 10/1995)3. To logout from another shell:
logout Not login shell. exit logout
The user tries to logout from a shell that is not a login shell. They exit from this shell and are then able to logout.