Previous Section: Command Line Format
The Bourne, Korn, and POSIX shells support interactive multiline commands. If the shell requires more input to complete the command, the secondary prompt (>) will be issued after you enter the carriage return. Some commands require closing commands, and some characters require a closing character. For example, an opening if requires fi to close, opening parentheses require closing parentheses, and likewise an opening apostrophe requires a closing apostrophe.
If you enter a command incorrectly, as illustrated on the slide, the shell will issue you a secondary prompt. A special key sequence should be defined to interrupt the currently executing program. Commonly [Ctrl] + [c] will terminate the currently running program and return the shell prompt. You can issue the "stty -a" command to confirm the interrupt key sequence for your session.
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