The terminal input may be abnormal on UNIX-based OS.
--The entered characters are not displayed --No line breaks on return input
In my experience, I get into this state after interactively running and exiting the version of the python interpreter installed on MacOS X with macports. The solution is to start a new terminal, but there is a slightly easier way to fix it.
Run the following command:
$ stty sane
This seems to happen if the running application changes the special characters in terminal and is not restored to its original settings when the application is closed.
stty is a command to display or change the terminal settings, and the
sane option has the effect of making special characters the default settings.