Learning Unix for Mac OS X Panther

The Unresponsive Terminal

During your Unix session, your terminal may not respond when you type a command, or the display on your screen may stop at an unusual place. That’s called a “hung” or “frozen” terminal or session. Note that most of the techniques in this section apply to a terminal window, but not to nonterminal windows such as a web browser.

A session can hang for several reasons. For instance, your computer can get too busy; the Terminal application has to wait its turn. In that case, your session resumes after a few moments. You should not try to “un-hang” the session by entering extra commands, because those commands will all take effect after Terminal comes back to life.

Tip

If your display becomes garbled, press Control-L. In the shell, this will clear the screen and display the prompt. In a full-screen program, such as a text editor, it will redraw the screen.

If the system doesn’t respond for quite a while (how long that is depends on your individual situation; ask other users about their experiences), the following solutions usually work. Try the following steps in the order shown until the system responds:

Press the Return key once.

You may have typed text at a prompt (for example, a command line at a shell prompt) but haven’t yet pressed Return to say that you’re done typing and your text should be interpreted.

Try job control (see Chapter 7); type Control-Z.

This control key sequence suspends a program that may be running and gives you a shell prompt. ...