When you log off a session in tty*, the screen does not get cleared before the login prompt is shown. This way, other people can see what you where doing last, which is IMO a security issue. Why isn't the screen cleared by default in Zenwalk?

The screen is not cleared because neither users nor root have a .bash_logout file in their home directory in the default config.

To fix this issue, create a ~/.bash_logout file and add the following lines to it:

The first line is to make sure exiting the shell will lead to a log out.