1ttyctl -fu 2 The -f option freezes the tty, and -u unfreezes it. When the 3 tty is frozen, no changes made to the tty settings by external 4 programs will be honored by the shell, except for changes in the 5 size of the screen; the shell will simply reset the settings to 6 their previous values as soon as each command exits or is sus- 7 pended. Thus, stty and similar programs have no effect when the 8 tty is frozen. Without options it reports whether the terminal 9 is frozen or not. 10