How come macports does not recognize "exit" ?

[Yves de Champlain]

--->  Fetching XFree86

Error:
                     You have an Apple X11 installation already.
                         MacPorts will not overwrite it.

                     If you really want to use XFree86 instead,
                         please move it aside first :

                             sudo mv /usr/X11R6 /usr/X11R6.apple

Error: Target org.macports.fetch returned: invalid command name "exit"
Error: Status 1 encountered during processing.

yves